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CIPANP is a conference series designed to explore common areas of interest to scientists working in elementary particle physics, nuclear physics, nuclear and particle astrophysics, and cosmology. Topics include research focused on the study of fundamental interactions, elementary particles, nucleons and nuclei, astrophysical phenomena, and cosmic rays. In many cases, these distinct areas are attempting to answer the same fundamental questions about our universe. Experiments in each area typically also require input from the other areas to properly extract and interpret results from their data. CIPANP brings these communities together every three years in a unique setting that fosters collaboration among these scientific disciplines.
The E989 collaboration has published the most precise measurement of the muon anomalous magnetic moment $a_\mu$ with an uncertainty of $\mathrm{460\,ppb}$ in 2021. The new experimental world average of $a_\mu$ deviates by 4.2 standard deviations from the Standard Model prediction provided by the Muon g-2 Theory Initiative. The emerging results from ab-initio lattice QCD calculations allow to scrutinize this tantalizing hint for physics beyond the Standard Model for the first time in a three way comparison. To extract the value of $a_\mu$ a clock comparison experiment is performed with spin-polarized muons confined in a superbly controlled electric and magnetic field environment. The deviation of the Larmor from the cyclotron frequency, the anomalous spin precession frequency, is determined while a high-precision measurement of the magnetic field environment is performed using nuclear magnetic resonance techniques. I will discuss the most recent result from the first science data run in 2018 and will report on the experimental improvements implemented to achieve the ultimate goal of $\mathrm{140\,ppb}$ uncertainty on $a_\mu$.
At Jefferson Lab, high luminosity electron beam are used to perform precision measurements on asymmetric nuclei including 3H, 3He, 48Ca, and 208Pb. Those nuclear system with imbalanced number of protons and neutrons provide a unique testing ground for isospin and flavor dependent effects in nuclear and nucleon structure. The recent Hall A Tritium Project which used the simplest many-body system, 3H and 3He to extract the neutron structure function, the nucleon-nucleon short-range correlation, and the nucleus charge radii. Unique information also came from measurements with Ca48 and Pb208 which provide a nearly saturated, neutron-rich nuclear environment. In this talk, I will discuss some of those recent results and also related measurements in the near future.
The 3D parton structure of strongly interacting systems is encoded in generalized and transverse-momentum-dependent parton distributions. We discuss the status of this very active research field and identify open questions. This includes a brief discussion of the overarching 5D partonic Wigner functions and the prospects of related studies at the future electron ion collider (EIC).
Cosmic Physics and Dark Energy, Inflation, and Strong-Field Gravity
The Cosmic Microwave Background (CMB) provides us both with a snapshot of the early Universe and with a backlight that illuminates all the later-developing structure. The statistics of this light provide an avenue to detect beyond-the-standard-model physics from inflationary gravitational waves or light relic particles. The growth of large-scale structure, measured by gravitational lensing of the CMB, provides information on the mass of neutrinos and on dark energy. Both the intensity and the polarization of the microwave light are crucial. Electron scattering of CMB photons allows us to find distant galaxy clusters via their gas content. With good time resolution, CMB surveys can identify and measure variable and transient objects from flaring stars to gamma-ray bursts to supermassive black holes in active galactic nuclei. These surveys can play a role in multimessenger astronomy. I will briefly tour ground-based experimental efforts at the South Pole and in Chile, including South Pole Observatory, Simons Observatory, and their successor, CMB-S4, a project highly rated by the Decadal Survey of Astronomy and Astrophysics.
Gravitational lensing of the cosmic microwave background is a powerful probe of the distribution of matter in the post-recombination Universe. Combining CMB lensing with galaxy surveys at different redshifts provides a tomographic view of the growth of structure, improving cosmological constraints. Using Planck CMB lensing and unWISE infrared galaxies, we find $S_8 \equiv \sigma_8 \sqrt{\Omega_m/0.3} = 0.784 \pm 0.015$. This result agrees well with $S_8$ measured from the weak lensing surveys DES and KiDS, and is 2.4-$\sigma$ below the Planck value. I will also discuss the prospects for constraining local primordial non-Gaussianity ($f_\textrm{NL}$) with CMB lensing cross-correlations, by measuring the scale-dependence of the galaxy bias on very large scales. Galaxy survey systematics can create spurious power at large scales in the auto-correlation, mimicking the scale-dependent bias signal and degrading the constraining power. Cross-correlations are cleaner than auto-correlations since systematics in each survey are not correlated, thus providing an alternative route to large-scale structure $f_\textrm{NL}$ constraints.
Gravitational waves from black holes and neutron stars are standard candles, the only input needed to infer their luminosity distance being Einstein's general theory of relativity. Combined with follow-up electromagnetic observations to measure the redshift of their hosts will provide a precision tool for calibration-free cosmology. Over the next decade we can expect the current generation of LIGO and Virgo detectors and their upgrades to resolve the Hubble tension. Future observatories such as the Cosmic Explorer will help determine the nature of dark energy.
Dark Matter
LUX-ZEPLIN (LZ) is a low-background, multi-detector dark matter experiment centered on a time projection chamber (TPC) utilizing a 7 t liquid xenon target to observe dark matter interactions. It is currently being operated 4850 ft underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota. In this talk, I will give an overview of the LZ project and present an analysis of the first 60 live days of data that looks for evidence of Weakly Interacting Massive Particles (WIMPs).
Understanding the nature of Dark Matter (DM) is one of the open issues in modern physics. In this context, XENON project aims to lead the effort on DM direct detection using ton-scale xenon dual-phase time projection chamber technology, operating in a low background environment. The status of XENONnT detector, running at the underground LNGS (L'Aquila, Italy) laboratories, will be shown. The preliminary results will be discussed as well as the foreseen goals.
The XENONnT experiment, located at the INFN Laboratori Nazionali del Gran Sasso (LNGS) in Italy, uses a dual-phase xenon time projection chamber with a liquid xenon target of 5.9 tonnes. The electronic recoil (ER) background in the (1, 30) keV region is measured to be (16.1±1.3) events/(tonne×year×keV), five times lower than that in XENON1T and the lowest ever achieved in a dark matter detector. In this presentation, I will report on a blind analysis of low-energy ER data from the first science run of XENONnT, aimed at investigating the excess observed by XENON1T. With an exposure of 1.16 tonne-years, no excess is observed above background and new limits are set on solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter. The XENON1T excess, modeled as a 2.3 keV mono-energetic peak, is excluded with a statistical significance of 4 sigma.
LUX-ZEPLIN (LZ) is a direct dark matter detection experiment aiming to detect rare events resulting from the scattering of Weakly Interacting Massive Particles (WIMPs). It employs a dual-phase xenon time projection chamber (TPC) with an active mass of 7 tonnes (5.6 tonne fiducial), surrounded by an instrumented xenon skin and liquid scintillator active vetoes. Significant effort has been made to achieve an unprecedented low background rate within its fiducial volume, including extensive detector material screenings, an inline radon removal system, and in-house xenon purification, to reach a target sensitivity of 1.4 x 10$^{-48}$ cm2 at 40 GeV/c$^2$. This talk will detail the backgrounds for the first LZ WIMP search results.
Despite its abundance, little is known about the particle nature of dark matter. Liquid argon-based detectors deployed in underground laboratories are powerful probes for direct detection dark matter searches, due to their scalability to large target masses, the low price of argon, their strong particle identification power using pulse shape discrimination to separate electronic and nuclear recoils, their high signal yields enabling low energy thresholds, and the exceptional purity that they can reach. Because of these properties, argon-based detectors make sensitive and versatile tools for searching for a variety of dark matter candidates, and they can serve as observatories for astrophysical neutrinos. This talk will present past, current, and future dark matter searches with argon-based detectors, along with technological advances that have been made to optimize the detectors' reach. Special attention will be paid to intersections between these efforts and other fields.
Physics at High Energies
Measurements of the fundamental properties of the Higgs boson are presented, including its mass, width, and the CP properties of its coupling in various production modes and decay channels.
Heavy Flavors and the CKM Matrix
We are presenting our ongoing lattice QCD study on $B - \bar{B}$ mixing on several RBC/UKQCD and JLQCD ensembles with 2+1 dynamical-flavour chirally symmetric domain wall fermions, including physical-pion-mass ensembles. The inverse lattice spacings range from a coarse 1.7 GeV to a very fine 4.5 GeV, allowing us to simulate near the b-quark mass. We extract bag parameters $B_{B_d}$ and $B_{B_s}$ both for the standard-model operator as well as the four BSM operators. On each ensemble, we are simulating a range of heavy-quark masses from below the charm-quark mass towards the bottom-quark mass, with one data point reaching about 75% of $m_{\eta_b}$.
A rich set of new results from the LHCb experiment are reported. Searches of CP violations in the beauty and charm sector have been performed with a variety of techniques offering new insights into the CP violation phenomenon. In this presentation, an updated status of charm-mixing parameters is also given. These measurements are of great importance to test the Standard Model's assumptions and hint at possible sources of New Physics.
Precision Physics at High Intensities
The PIONEER experiment [1] will investigate rate pion decays and aims to measure the branch-
ing ratio $R_{e/μ} ≡ Γ(π^+ → e^+ν(γ))/Γ(π^+ → μ^+ν(γ))$ with a precision of 0.01 % in its first phase.
This marks an improvement by an order of magnitude with respect to the current experimental
uncertainty and would match the uncertainties of the theoretical predictions. This allows to test
lepton flavour universality at an unprecedented level and probe mass scales up to the PeV range.
In the second phase of the experiment, a 0.06% measurement of the branching ratio of the pion
beta decay, $R_{πβ} ≡ Γ(π^+ → π0e^+ν(γ))/Γ($all$)$, will provide another window into potential physics
beyond the SM by exploring the Cabibbo angle anomaly and by providing a theoretically pristine
measurement of |Vud|. In addition, further rare decays involving various exotic particles such as
ALPs or sterile neutrinos can be searched for with unprecedented sensitivities.
The experimental design incorporates lessons learned from the previous generation PIENU [2]
and PEN/PIBETA [3, 4] experiments at TRIUMF and PSI. It involves stopping an intense pion
beam in a novel active target (ATAR), which is surrounded by a 3π sr, 25 radiation length (X0)
electromagnetic calorimeter to determine the energy of the final state products. A tracker is placed
between ATAR and calorimeter to link pion stopping events in ATAR to calorimeter showers. Each
of the subsystems is being actively modeled in simulation to ensure we will be able to reach our
experimental goal.
Here, we present the theoretical motivation for PIONEER, discuss the experiment design, and
show recent results from simulations and a first beam development campaign at the PSI PiE5
beamline.
[1] PIONEER Collaboration, arXiv:2203.01981 [hep-ex]
[2] A. Aguilar-Arevalo et al. (PIENU), Phys. Rev. Lett. 115, 071801 (2015), arXiv:1506.05845 [hep-
ex].
[3] C. J. Glaser et al. (PEN) arXiv:1812.00782 [hep-ex]
[4] D. Počanić et al. Phys. Rev. Lett. 93, 181803 (2004)
Limits on the charged lepton flavor violating (CLFV) process of $\mu\rightarrow e$ conversion are expected to improve by four orders of magnitude due to the next generation of experiments, Mu2e at Fermilab and COMET at J-PARC. While the kinematics of the decay of a trapped muon are ideal for detecting a signal of CLFV, the intervening nuclear physics presents a significant roadblock to the interpretation of experimental results. We introduce an effective theory of $\mu\rightarrow e$ conversion formulated at the nuclear scale, which factorizes the nuclear physics from the CLFV leptonic physics, sequestering the latter quantity into unknown low-energy constants (LECs) that are probed directly by experiments. Utilizing state-of-the-art shell-model calculations of nuclear response functions, we estimate the limits that can be obtained on these LECs if the next-generation experiments achieve their design sensitivity.
Lepton-flavor-violating decays of light pseudoscalars, $P=\pi^0,\eta,\eta'\to\mu e$, are stringently suppressed in the Standard Model up to tiny contributions from neutrino oscillations, so that their observation would be a clear indication for physics beyond the Standard Model. However, in effective field theory such decays proceed via axial-vector, pseudoscalar, or gluonic operators, which are, at the same time, probed in spin-dependent $\mu\to e$ conversion in nuclei. We derive master formulae that connect both processes in a model-independent way in terms of Wilson coefficients, and study the implications of current $\mu\to e$ limits in titanium for the $P\to\mu e$ decays. We find that these indirect limits surpass direct ones by many orders of magnitude.
based on: arXiv:2204.06005 [hep-ph]
The AlCap experiment is set to measure comprehensive details of charged particles, photons and neutrons emitted after nuclear muon capture in Al and Ti at PSI, Switzerland. For photons, a high purity Ge detector was used to capture the spectra from these targets. In addition to those targets, measurements were made on W, Pb, stainless steel, poly and mylar to check for possible interferences near gammas/X-rays of interested. In this talk, I will describe the experiment and present the results for the first time.
Flavor-violating processes in the lepton sector have highly suppressed branching ratios in the standard model, mainly due to the tiny neutrino mass. This means that observing lepton flavor violating processes, such as muonium-antimuonium oscillations, in the next round of experiments would indicate the presence of physics beyond the standard model (BSM). We review theoretical calculations of the mass and width differences in the muonium-antimuonium system and discuss the implications of the experimental measurements of those parameters on constraints on new physics scales probed in muonium oscillations.
Neutrino Masses and Neutrino Mixing
Super-Kamiokande (SK) is a 50 kiloton water-Cherenkov detector located in Japan which has collected over 20 years of atmospheric neutrino data. This talk will present the latest results from the SK atmospheric neutrino oscillation analysis, including events from an expanded fiducial volume and new data taken following major detector refurbishment work in 2018, which together result in a 30% increase in exposure over the previous analysis. The atmospheric neutrino data are also analyzed including neutrino and anti-neutrino mode data from the T2K experiment, made possible by re-weighting SK Monte Carlo to T2K flux and cross section inputs.
Precision measurements from long-baseline neutrino experiments are revealing details about neutrino interactions, masses, and mixing properties. The NOvA experiment employs a 14-kiloton liquid scintillator detector to collect neutrinos after an 800-kilometer journey from Fermilab to northern Minnesota. With a growing collection of neutrino events, NOvA is extending its reach into the three-flavor oscillation parameter space and beyond. This talk will present a brief overview of the NOvA experiment and its recent results, including the latest oscillation analyses, interaction physics, sterile neutrino searches, and investigations beyond accelerator neutrinos.
Daya Bay is an international neutrino reactor experiment in southern China. Eight identical gadolinium-doped liquid scintillator detectors located in three experimental halls at different distances from 360 m to 1900 m from the nuclear power plant reactors have collected a unique sample of more than 5.5 million electron-antineutrino interactions between 2011 and 2020. The high-precision determination of the neutrino energy spectra by different detectors allows by far the most accurate measurement of the smallest mixing angle θ13 and also the measurement of the large difference of neutrino masses Δm2 with the same precision as in accelerator neutrino experiments. The huge number of interactions recorded and the time evolution of the fuel in the reactors allowed the first measurements of neutrino spectra from nuclear fission of the isotopes 235U and 239Pu. The results of the Daya Bay experiment have also contributed to constraining the parameters of possible sterile neutrinos.
In the past decade, experimental neutrino physics has evolved to be one of the most exciting and rapidly growing fields of scientific research. In particular, the discovery of neutrino oscillations is a significant step towards understanding whether neutrinos violate the CP-symmetry. Deep Underground Neutrino Experiment (DUNE) and Hyper-Kamiokande are two long-baseline neutrino experiments that will start up in the next decade to precisely measure this CP violation. In addition to precisely measuring the CP-violation, DUNE will use an intense beam of neutrinos and a highly capable suite of near detectors and far detector modules to precisely measure neutrino oscillation parameters, observe supernova burst neutrinos, and detect rare processes such as proton decay. JUNO will measure neutrino mass ordering and study neutrino oscillations at medium baselines. Several experiments are planned, including Fermilab’s short baseline program, to determine the source of anomalies observed in short-baseline neutrino experiments. The goal of this talk is to provide an overview of these neutrino experiments that will be launched over the next decade and will lead the field to new discoveries.
Future cosmological observatories, such as CMB-S4, the Thirty Meter Telescope, and the Vera Rubin Observatory, will give the highest precision data on the universe ever measured. The convolution of this data may allow theorists to posit new Beyond Standard Model (BSM) physics in operation during earlier phases of the universe. In the work presented here, we focus on the transition of neutrinos from the tightly-coupled regime of equilibrium to the decoupled epoch of free-streaming. Neutrino decoupling precedes the freeze-out of weak isospin-changing and nuclear reactions. The out-of-equilibrium neutrino distributions ultimately influence late time observables such as primordial abundances and radiation energy density. We use a parameterization of the neutrino distribution fields to describe the time evolution of those functions during this weak decoupling period. Our model is an excellent description of the system in the energy region that captures 64$\%$ of the total neutrino density. Within this region, our polynomial fitting never deviates more than 0.05$\%$. We discuss how the coefficients of the parameterization are related to the expected number, energy, and energy fluctuations of the system. Our results and methodology have implications for characterizing the standard or BSM theories of cosmology.
Tens of MeV neutrinos, e.g. from the stopped pion or core-collapse supernova sources, scatter off the target nucleus in the detector either via a coherent elastic or the inelastic process and allow the study of a variety of SM and BSM processes. The precision of the coherent elastic neutrino nucleus scattering (CEvNS) process, where the scattered nucleus remains in its ground state, is limited by the precision with which the underlying weak form factor of the nucleus is known. Fully exploring the potential of CEvNS experiments requires a detailed description of underlying nuclear structure embedded in the weak form factor. Additionally, CEvNS experiments at stopped pion sources are also powerful avenues to measure inelastic cross sections, where neutrino excites the target nucleus to low-lying nuclear states and is subject to more detailed underlying nuclear structure and dynamics, that are vital in constraining supernova physics prospects of future neutrino experiments. In this talk, I will present an overview of CEvNS and inelastic neutrino-nucleus interactions in the tens of MeV region, constraining those are vital in disentangling beyond the Standard Model physics signals from the SM signals in neutrino experiments.
Parton and Gluon Distributions in Nucleons and Nuclei
The development of a TeV-scale muon accelerator and storage ring provides enormous scientific potential not only for a mu+mu- collider, but also for deep inelastic scattering in a completely new regime when a TeV muon beam is collided with a hadron beam. For example, if the approved Electron-Ion Collider at BNL were eventually upgraded with a TeV muon beam replacing its low energy electron ring, a $Q^2$ reach of up to $10^{-6}$ GeV$^2$ is accessible and a parton momentum fraction $x$ down to $1.0\times 10^{-5}$ can be probed. This coverage is equivalent to that of the proposed LHeC, although the facility at BNL offers the additional possibilities of polarized beams to study spin dependencies and a large variety of ion beams. Therefore, such a facility is of great interest to both particle and nuclear physics communities.
We report on studies of the physics potential at such muon-ion colliders that could be realized at the BNL facility as well as at other sites such as the CERN LHC. In particular, we summarize and contrast the kinematics in such high momentum muon-ion collisions with other collider proposals, and discuss the prospects for electroweak and QCD measurements. The sensitivity to very low values of $x$ will allow a careful study of the expected region of gluon saturation in nuclei. We also examine the potential for Higgs boson studies in muon-proton collisions through calculations of the production cross sections for different beam energies and polarizations, as well as show the kinematic distributions of the decay products and of the scattered lepton and parton. Finally, we discuss some detector design considerations and the needed coverage and resolution for measurements. A common feature for the experiments at such a muon-ion collider facility is the need for a forward muon spectrometer.
The proposed Electron-Ion Collider (EIC) will utilize high-luminosity high-energy electron+proton ($e+p$) and electron+nucleus ($e+A$) collisions to solve several fundamental questions including searching for gluon saturation and studying the proton/nuclear structure. Advanced detector technologies, such as the low material budget fine spatial resolution Monolithic Active Pixel Sensor (MAPS), will enable high precision heavy flavor hadron and jet measurements at the future EIC. Due to their high masses ($M_{c,b} > \Lambda_{QCD}$), heavy quarks do not transfer into other quarks or gluons once they are produced. This feature makes the heavy flavor product an ideal probe to explore how a heavy flavor hadron is formed from a heavy flavor quark, the heavy quark hadronization. A series of heavy flavor hadron and jet simulation studies have been carried out with the newly developed analysis framework, which consists of the event generation in PYTHIA, detector performance of recent EIC detector conceptual designs, QCD and beam remanent background embedding. We will present reconstructed heavy flavor hadron and jet mass (transverse momentum) spectrums, the projected nuclear modifications of heavy flavor hadrons inside jets, and heavy flavor jet substructure distributions in $e+p$ and $e+A$ collisions. These proposed EIC heavy flavor measurements will provide a unique path to constrain the accessed gluon parton distribution functions within the high Bjorken-x ($x_{BJ} > 0.1$) region, explore the flavor dependent fragmentation functions and heavy quark nuclear transport properties in nuclear meidum, which can constrain the initial and final state effects for previous and ongoing heavy ion measurements at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC).
Ultra-peripheral collisions (UPC) are events characterised by large impact parameters between the two projectiles, larger than the sum of their radii. In UPCs, the protons and ions accelerated by the LHC do not interact via the strong interaction and can be regarded as sources of quasireal photons.
Vector meson (e.g. \jpsi and \psip) photoproduction in UPC is quite interesting since it is sensitive to the low-$x$ gluon density. The data set collected with pPb UPCs in ALICE is particularly useful to probe for gluon saturation. The energy dependence of the exclusive photoproduction of \jpsi off proton targets as a function of the centre-of-mass energy of the photon-proton system, $W_{\gamma p}$, measured in pPb collisions at 5.02 TeV will be shown, together with the recent points at 8.16 TeV.
The measurements carried out using Pb--Pb data instead address phenomena such as gluon shadowing. Owing to the statistics available from Run 2 data, the ALICE Collaboration has been able to carry out differential measurements, e.g. it has measured the rapidity-differential cross section of coherent \jpsi production in Pb--Pb UPCs, and the $t$-dependence, and compared it with models incorporating nuclear shadowing effects, thus providing a new tool to investigate the gluon structure at low Bjorken-$x$.
In addition, measurements of coherently photoproduced \jpsi in different conditions, characterised by different average impact parameters, e.g. the recent ALICE measurement of coherent \jpsi photoproduction in peripheral collisions, provide promising tools for the resolution of the ambiguity in Bjorken-$x$ which arises in symmetric A--A UPCs.
On behalf of the ZEUS Collaboration.
The azimuthal decorrelation angle between the leading jet and scattered lepton in deep inelastic scattering is being studied in the ZEUS detector at HERA. The data was taken in the HERA II data-taking period and corresponds to an integrated luminosity of 330 pb−1. Azimuthal angular decorrelation has been proposed to study the Q2 dependence of the evolution of the transverse momentum distributions (TMDs) and understand the small-x region, providing unique insight to nucleon structure. Previous decorrelation measurements of two jets have been performed in proton-proton collisions at very high transverse momentum; these measurements are well described by perturbative QCD at next-to-leading order. The azimuthal decorrelation angle obtained in these studies shows good agreement with predictions from QCD calculations; however, there are parts of the phase space for which deviations of up to 20% are observed. Dedicated theoretical predictions are to be tested in the future.
The Electron-Ion Collider (EIC), to be built at Brookhaven National Lab within this decade, will provide high-precision access to the gluon and sea-quark dominated region of the nucleon. With luminosities of 10$^{33-34}$ cm$^{-2}$s$^{-1}$, centre of mass energies 20-140 GeV, highly polarised electron and proton / light-ion beams and hermetic detectors, the collider will enable measurements of rare, exclusive processes in a very large, previously-unchartered region of the nucleon phase space. Exclusive processes such as deeply virtual Compton scattering (DVCS), meson production (DVMP) or time-like Compton scattering (TCS) give access to Generalised Parton Distributions (GPDs), which can be interpreted as relating transverse position of partons to their longitudinal momentum. GPDs, which yield 3D tomographic images of the nucleon, map out its pressure distribution and shed light on the contribution of orbital angular momentum to nucleon spin, are the focus of much experimental effort in electron scattering, but they are currently minimally constrained far below the valence region. We present studies of exclusive processes at the EIC which will greatly constrain our knowledge of GPDs in the quark-gluon sea region.
Dark Matter
With its excellent energy resolution and ultra-low backgrounds, the high-purity germanium detectors in the Majorana Demonstrator enable several searches for beyond the Standard Model physics. These range from the primary neutrinoless double beta decay search to searches for several classes of exotic dark matter models, axions, and tests of quantum mechanical conservation laws. In this talk, we present several of these studies which focus on the low-energy 1–100 keV region of a 37 kg-year exposure collected between May 2016 and November 2019. These enriched germanium detectors were operated in a low-background, ultra-low radioactivity shield and cryostat at a depth of 4300 mwe at the Sanford Underground Research Facility before being transferred to the LEGEND-200 experiment. In this talk, we present new experimental limits for keV-scale sterile neutrino dark matter, fermionic dark matter absorption, sub-GeV dark matter 3-2 body scattering, and bosonic dark matter, and discuss the status of beyond-Standard Model physics searches in germanium detectors.
This material is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics and Nuclear Physics Programs of the National Science Foundation, and the Sanford Underground Research Facility.
The LUX-ZEPLIN (LZ) detector consists of 7 tonnes (5.6 tonnes fiducial) of liquefied xenon in a
dual-phase Time Projection Chamber (TPC), which is sensitive to the nuclear and electron recoils
induced by Weakly Interacting Massive Particles (WIMPs). Among the various type of background
particles, neutrons pose a great threat to the WIMPs searches due to the indistinguishable nuclear
recoil. Surrounding the liquid xenon cryostat is an Outer Detector veto system with the primary
aim of vetoing neutron single-scatter events in the liquid xenon. The Outer Detector consists of
approximately 17 tonnes of gadolinium-loaded liquid scintillator (Gd-LS) confined to acrylic tanks
surrounding the cryostat and 228000 litres of water as the outermost layer. The volume is monitored
by 120 inward-facing 8-inch photomultiplier tubes. The Outer Detector is used to characterize the
external background, increasing the fiducial volume of LZ by 70%. I will present the design and
performance of the LZ Outer Detector.
Potassium-40 ($^{40}$K) is a naturally-occurring, radioactive isotope impacting understanding of nuclear structure, geological ages spanning timescales as old as the Earth, and rare-event searches including those for dark matter and neutrinoless double beta decay. In many advancing fields, the accelerating precision required for new discoveries has been limited by knowledge of the $^{40}$K decay scheme. This long-lived radionuclide undergoes electron capture decays to either the excited or ground state of its Ar daughter, of which the latter has previously not been measured, and estimates of its branching ratio are highly variable ($(0-0.8)\%$). In many dark matter searches, $^{40}$K contamination produces a challenging 3 keV background from these electron capture decays in the expected direct-detection signal region, and the ill-known ground state contribution may affect interpretation of dark matter results, such as that of DAMA/LIBRA. In geochronology, the common omission of this decay branch may affect calculated ages. This rare third-forbidden unique decay additionally provides an estimate for the associated weak axial vector coupling constant, the quenching of which affects calculated half-lives of neutrinoless double-beta decay. The KDK (``potassium decay") experiment is carrying out the first measurement of this elusive $^{40}$K branch using a coincidence technique between a high-resolution silicon drift detector to observe X-rays, and a high-efficiency ($\sim 98\%$) Modular Total Absorption Spectrometer (Oak Ridge National Labs) to tag gammas, to differentiate ground and excited state electron capture decays of $^{40}$K. We report on the $^{40}$K analysis, and the extent of its applications.
Physics at High Energies
Recent CMS results on Higgs physics are presented
In the Standard Model, the ground state of the Higgs field is not found at zero but instead corresponds to one of the degenerate solutions minimising the Higgs potential. In turn, this spontaneous electroweak symmetry breaking provides a mechanism for the mass generation of nearly all fundamental particles. The Standard Model makes a definite prediction for the Higgs boson self-coupling and thereby the shape of the Higgs potential. Experimentally, both can be probed through the production of Higgs boson pairs (HH), a rare process that presently receives a lot of attention at the LHC. In this talk, the latest HH searches by the ATLAS experiment are reported, with emphasis on the results obtained with the full LHC Run 2 dataset at 13 TeV. In the case of non-resonant HH searches, results are interpreted both in terms of sensitivity to the Standard Model and as limits on the Higgs boson self-coupling. Extrapolations of recent HH results towards the High Luminosity LHC upgrade are also discussed. Search results on new resonances decaying into pairs of Higgs bosons are also reported.
The discovery of the Higgs boson with the mass of about 125 GeV completed the particle content predicted by the Standard Model. Even though this model is well established and consistent with many measurements, it is not capable to solely explain some observations. Many extensions of the Standard Model addressing such shortcomings introduce additional Higgs-like bosons which can be either neutral or charged. Exotic decays of the Higgs boson also provide a unique window for the discovery of new physics, as the Higgs boson may couple to hidden-sector states that do not interact under Standard Model gauge transformations. Also, models predicting exotic Higgs boson decays to pseudo-scalars can explain the g-2 and flavour-sector anomalies, and the galactic centre gamma-ray excess if the additional pseudo-scalar acts as the dark matter mediator. This talk presents recent searches for additional low- and high-mass Higgs bosons, as well as decays of the 125 GeV Higgs boson to new particles, using LHC collision data at 13 TeV collected by the ATLAS experiment in Run 2.
Heavy Flavors and the CKM Matrix
Several experimental measurements of $b$-decays have suggested the presence of physics beyond the Standard Model (BSM). One set of such measurements are the decay modes $B\to D^{*+}\ell^- \bar{\nu}$ with $\ell = e, \mu,$ and $\tau$. A recent analysis of 2019 Belle data found $\Delta A_{FB} = A_{FB}(B\to D^{*} \mu\nu) - A_{FB} (B\to D^{*} e \nu)$ to be
$4.1\sigma$ away from the SM prediction. Improved simulation and analysis tools are needed in order to more e ectively probe these new physics (NP) possibilities. We have developed a
Monte-Carlo event generator tool based on the EVTGEN framework to simulate NP signatures in $B\to D^{*+}\ell^- \bar{\nu}$, which arise due to the interference between the SM and NP amplitudes. We have also simulated several example NP scenarios which are able to explain the $\Delta A_{FB}$ anomaly, while remaining consistent with experimental constraints. We also show that $\Delta$-type observables allow for de nite signals of NP by removing most QCD uncertainties from the form factors, and introduce several correlated bservables that allow for more sensitivity to NP.
One of the most persistent tensions in flavor physics is the $V_{cb}$ puzzle, a long standing tension between inclusive and exclusive determinations of the CKM matrix element $V_{cb}$. After lattice QCD has been applied extremely successfully in the calculation of physical quantities needed for the exclusive determination of $V_{cb}$ for many years, now also methods for computing inclusive observables on the lattice are available.
First results obtained using these methods at an unphysical $m_b$ are presented, systematically compared to the predictions the operator product expansion and future prospects are discussed.
Precision Physics at High Intensities
The Fermilab E989 Muon g-2 experiment is a precise measurement of the muon anomalous magnetic moment $a_{\mu}$ by detecting decays of muons stored in a ring. The first result of the E989 Muon g-2 experiment, with $a_{\mu}$ uncertainty of 460 ppb, deviated by 4.2 standard deviations from the Standard Model theory prediction. The goal of E989 is to reach the precise of 140 ppb in $a_{\mu}$. Two measurements: of the precession spin frequency, $\omega_a$, and of the shielded-proton Larmor precession frequency, $\tilde{\omega_p}’$ are needed in order to determine $a_{\mu}$. The frequency $\omega_a$ is measured by detecting decay positrons in 24 calorimeter detectors installed uniformly around the storage ring and by exploiting the parity violation in $\mu^+$ decay. The frequency $\tilde{\omega_p}’$ is determined from highly precise field measurements performed by using nuclear magnetic resonance (NMR) techniques. Three types of NMR probes are used to measure the field for different purposes. This paper will focus on the role of each NMR probe and the methods used to extract the frequency from the NMR probe data through the application of appropriately constructed NMR models in a non-uniform field. Finally, I will discuss the field systematic associated with the NMR techniques
The muon anomalous magnetic moment $(g-2)_{\mu}$ and the electric dipole moment are sensitive to new physics beyond the Standard Model (SM). There is a discrepancy between the Standard Model prediction for the $(g-2)_{\mu}$ and the values measured by the E821 collaboration at Brookhaven National Laboratory (BNL) and E989 collaboration at Fermilab at the more than $4 \sigma$ level. This may imply a presence of new physics, therefore, precise measurements of the muon anomaly with an independent method are crucial.
We aim to measure $(g-2)_{\mu}$ with a precision of 450 parts per billion
and to search for the electric dipole moment with a sensitivity of $1.5 \times 10^{-21} e \cdot$cm
in the initial phase with a method different from the E821 at BNL and E989 at
Fermilab experiments. To reach the target precision, we utilize a high-intensity proton beam at J-PARC and newly developed technique of reaccelerated thermal muon beam, which is produced by thermal muonium production followed by laser ionization and linear acceleration. We report experimental approaches, current status of each component of our experiment, and future prospects.
We present the recent lattice QCD computation of the hadronic vacuum polarization by the Budapest-Marseille-Wuppertal collaboration. We will also discuss ongoing improvements.
Neutrino Masses and Neutrino Mixing
The Karlsruhe Tritium Neutrino (KATRIN) experiment aims to make a precision mass measurement of the neutrino by leveraging the kinematics of tritium beta decay. High-precision spectroscopy is performed near the endpoint at 18.6 keV by employing a windowless gaseous tritium source combined with a MAC-E filter technique as an electron spectrometer. Being complementary to the search for neutrinoless double beta decay and the analysis of cosmological data, this direct neutrino mass measurement allows a model-independent way of approaching the neutrino mass scale to a design mass sensitivity of 0.2eV (90 % C.L.).
The required sensitivity demands high stability of hardware components, a precise understanding of systematic effects, and a low background. From early 2019, KATRIN is taking highly statistical tritium data. The 2019 data already provide a sub-eV sensitivity and a neutrino mass limit. In the meanwhile, significantly more data was recorded in a new spectrometer configuration. In addition to presenting the latest results, the current status of the experiment and the ongoing analyses will be reported.
The MAJORANA DEMONSTRATOR experiment searches for neutrinoless double-beta decay (0νββ) in 76Ge using p-type point contact (PPC) high purity germanium (HPGe) detectors. The data-taking for 0νββ by the DEMONSTRATOR has successfully completed in March 2021. The DEMONSTRATOR has developed traditional pulse-shape-based approaches to discriminate different types of events, such as multi-site (MS) events and single-site (SS) events. The collaboration is also exploring machine learning (ML) tools for event discrimination, such as neural networks. In this talk, we will discuss MAJORANA ML efforts. For example, the ML approach is used to tag pileup-event waveforms, due to both random coincidences in calibration data and real physics correlations. The talk will also discuss the interpretable ML models for SS and MS event discrimination where the attention mechanism is implemented to focus on the most important component of the waveform, and to enhance the network performance.
The LEGEND (Large Enriched Germanium Experiment for Neutrinoless Double-beta decay) project will search for neutrinoless double-beta decay in $^{76}$Ge, aiming to operate at the ton-scale in its second phase (LEGEND-1000). LEGEND uses liquid argon as an active veto and as a radiopure bulk shield. Penetrating cosmic ray muons can cause showers in liquid argon, generating free neutrons which can scatter or capture in sensitive detectors, resulting in in-situ cosmogenic backgrounds. A pre-conceptual baseline design of LEGEND-1000 has been developed by the collaboration. Using Geant4 simulations, changes in the baseline ton-scale LEGEND configuration are modeled and the effects of each modification on the muon-induced background are evaluated. The neutron transport and physics are also validated using a suite of comparison simulations between Geant4 and MCNP, another particle simulation software. In this presentation, we will discuss the LEGEND-1000 baseline design, potential changes to the baseline to mitigate muon-induced backgrounds, and comparisons of these changes using simulations.
Project 8 is an experiment that seeks to determine the electron-weighted neutrino mass via the precise measurement of the electron energy in beta decays, with a sensitivity goal of $40\,\mathrm{meV/c}^2$. We have developed a technique called Cyclotron Radiation Emission Spectroscopy (CRES), which allows single electron detection and characterization through the measurement of cyclotron radiation emitted by magnetically-trapped electrons produced by a gaseous radioactive source. The technique has been successfully demonstrated on a small scale in waveguides to detect radiation from single electrons, and to measure the continuous spectrum from tritium. In order to achieve the projected sensitivity, the experiment will require novel technologies for performing CRES in a multi-cubic-meter volume using magnetically trapped tritium atoms. In this talk, I will present a brief overview of the Project 8 experimental program, highlighting the latest results including our first tritium endpoint measurement and neutrino mass limit, and introduce the development of the techniques needed to deploy CRES at large scales.
This work is supported by the US DOE Office of Nuclear Physics, the US NSF, the PRISMA+ Cluster of Excellence at the University of Mainz, and internal investments at all collaborating institutions.
The Cryogenic Underground Observatory for Rare Events (CUORE) is the first bolometric experiment searching for neutrinoless double beta decay ($0\nu\beta\beta$) decay that has reached the one-tonne mass scale. The detector, located at the Gran Sasso National Laboratory in Italy, consists of an array of 988 TeO$_2$ crystals arranged in a compact cylindrical structure of 19 towers. CUORE began its first physics data run in 2017 at a base temperature of about 10~mK and in April 2021 released its third result of the search for $0\nu\beta\beta$, corresponding to a tonne-year of TeO$_2$ exposure. This is the largest amount of data ever acquired with a solid state detector and the most sensitive measurement of $0\nu\beta\beta$ decay in $^{130}$Te ever conducted, with a median exclusion sensitivity of $2.8\times10^{25}$ yr. We find no evidence of $0\nu\beta\beta$ decay and set a lower bound of $2.2\times10^{25}$ yr at a 90\% credibility interval on the $^{130}$Te half-life for this process. In this talk, we present the current status of CUORE search for $0\nu\beta\beta$ with the updated statistics of one~tonne$\cdot$yr. We will also give an update of the CUORE background model and the measurement of the $^{130}$Te $2\nu\beta\beta$ decay half-life with an exposure of 300.7 kg$\cdot$yr.
Parton and Gluon Distributions in Nucleons and Nuclei
In this talk we present an overview of the state-of-the-art extractions of unpolarized and helicity parton distribution functions (PDFs). These analyses include the latest data from the Large Hadron Collider and Relativistic Heavy Ion Collider, providing new information and new levels of precision on the PDFs.
The Relativistic Heavy Ion Collider (RHIC) has been serving the community as the first and only polarized proton-proton ($pp$) collider in the world, providing unique perspectives on the inner structure of the proton.
In particular, $W$ bosons produced at RHIC are used to probe the light flavor structure in the proton.
At leading order, $W$ bosons arise in $pp$ collisions via Drell-Yan type processes, $q\bar{q} \rightarrow W$, which directly provide sensitivity to the anti-quark densities in the proton.
The large momentum scale set by the $W$ mass allows for perturbative calculations needed for theory predictions.
The STAR experiment at RHIC measures the $W$ boson production in order to probe the flavor asymmetry between the $\bar{d}$ and $\bar{u}$ distributions.
The $W$ bosons produced at the STAR interaction point typically are typically tagged via their leptonic decay, $W \rightarrow e\nu$, which leaves a characteristically large imbalance in energy deposit in the STAR electromagnetic calorimeter (EMC).
The STAR barrel (BEMC) and endcap (EEMC) calorimeters cover the mid ($|\eta| < 1$) and intermediate ($1 < \eta < 2$) rapidities, respectively, providing kinematic coverage over a proton momentum fraction range of $0.06 < x < 0.4$.
Presented in this talk are the recent results of measurements of $W$ and $Z/\gamma^*$ cross sections and their ratios via leptonic-decay tagging, using the STAR $pp$ collision data at a center-of-mass energy of $\sqrt{s} = 510\,\mathrm{GeV}$ collected in 2011, 2012, 2013 and 2017, corresponding to an integrated luminosity of $\sim 700\,\mathrm{pb^{-1}}$.
On behalf of the H1 and ZEUS Collaborations.
Eur. Phys. J. C82 (2022) 243
The HERAPDF2.0 ensemble of parton distribution functions (PDFs) was introduced in2015. The final stage is presented, a next-to-next-to-leading-order (NNLO) analysis of theHERA data on inclusive deep inelasticepscattering together with jet data as published bythe H1 and ZEUS collaborations. A perturbative QCD fit, simultaneously ofαs(M2Z) andand the PDFs, was performed with the resultαs(M2Z)=0.1156±0.0011 (exp)+0.0001−0.0002(model+parameterisation)±0.0029 (scale). The PDF sets of HERAPDF2.0Jets NNLO were de-termined with separate fits using two fixed values ofαs(M2Z),αs(M2Z)=0.1155 and 0.118,since the latter value was already chosen for the published HERAPDF2.0 NNLO analysisbased on HERA inclusive DIS data only. The different sets of PDFs are presented, evalu-ated and compared. The consistency of the PDFs determined with and without the jet datademonstrates the consistency of HERA inclusive and jet-production cross-section data. Theinclusion of the jet data reduced the uncertainty on the gluon PDF. Predictions based on thePDFs of HERAPDF2.0Jets NNLO give an excellent description of the jet-production dataused as input.
Starting from the Weinberg formalism for the construction of fields for arbitrary spin, we propose an algorithm for the construction of the independent operators that enter the scattering amplitude associated with electromagnetic observables. This procedure is useful for the systematic study of the structure of hadrons and nuclei. In particular, it is very convenient in the case of spin-dependent observables. Since new features appear in the hadronic structure of higher spin targets, the investigation of their properties can improve our understanding of the strong force. As a proof of principle, we apply this method to the description of elastic electron-deuteron scattering. The result of calculations within Instant and Light-Front forms of dynamics is presented for the vector and axial electromagnetic form factors and is compared with the existing literature. We discuss potential extensions of the formalism to hard exclusive processes on the deuteron.
This research is partially supported by the National Science Foundation under grant number PHY-2111442.
After examining the mass and pressure decompositions of hadrons in the stress-energy-momentum tensor, it is found that the glue part of the trace anomaly can be identified as originated from the vacuum energy of the glue condensate and gives a CONSTANT restoring pressure which balances that from the traceless part of the Hamiltonian (quark and glue kinetic energies) to confine the hadron, much like the cosmological constant Einstein introduced for a static universe. From a lattice calculation of this anomaly in the charmonium, we deduce the associated string tension which turns out to be in good agreement with that from a Cornell potential calculation which fits the charmonium spectrum.
One notices that there is a close analogy with type II superconductors where the confining potential from the Ginzburg-Landau equation is the number of Cooper pairs times the energy gap of each pair. This gives a negative pressure to balance the those from the magnetic field energy in the normal phase and the kinetic energy of the supercurrent. Thus, all three confinement mechanisms mentioned above are due to the presence of a condensate.
A mystery of why the pion mass approaches zero at the chiral limit is solved. The pion mass can be
expressed by the sum of the sigma term and the trace anomaly. While the sigma term vanishes as \sqrt{m_q}, the trace anomaly has no quark mass dependence. Why does it approach zero at the chiral limit? A lattice calculation of the trace anomaly reveals that it changes sign in its spatial distribution as the quark mass decreases which is like the ring-shaped type II superconductor. This is perhaps the only example that the structure of the conformal symmetry breaking is dictated by the chiral symmetry breaking.
Particle and Nuclear Astrophysics
The Gupta-Meyer treatment of nuclei with long-lived isomers computes the effective internal equilibration rate by assuming that the higher-lying nuclear levels, through which the ground and isomeric states communicate, are in steady-statel [1]. The effective rate for transition between the ensemble of states associated with the ground state and the ensemble of states associated with the isomeric state then becomes a sum over probabilities of pathways between the ground and isomeric state. The treatment also permits the computation of nuclear partition functions for the ground-state and isomeric state ensembles. This allows the two ensembles to be included in the reaction network as separate species. This talk will present the Gupta-Meyer technique, discuss the nuclear physics data required for proper calculation of the reaction rates between the ensembles and between the ensembles and other network species, and illustrate some effects of isomers with network calculations of i-process and r-process nucleosynthesis. It will also present some open-source tools for computing relevant rates for nuclides with isomers and for incorporating those rates in a reaction network.
[1] Gupta, S. S. and Meyer, B. S. (2001) PRC, 64, 025805.
The role of nuclear isomers in astrophysical nucleosynthesis is gaining increased attention, as reactions on ground and isomeric states are both potentially important for determining the reaction rates and flow within the reaction network. A particular case is the odd-odd N=Z nuclides in the sd-shell, which play an important role in breakout from the CNO cycle in nova nucleosynthesis, affecting reaction flow, the nucleosynthesis end-point, and final abundances impacting potential astronomical observables. Because many of these nuclides have low-lying spin isomers, and the difference in structure between their ground and isomeric states leads to a different set of proton resonances in each case, it is important to constrain reactions on both ground and isomeric states.
Developments in radioactive-beam experiments are opening such opportunities, via direct and indirect techniques. An overview of recent measurements will be presented, with a particular focus on a campaign of experiments using the ORRUBA silicon detector array. This will include the first measurement using a new technique for manipulating ground/isomer content in reaccelerated beams without affecting ion optics, applicable to future measurements at the nascent Facility for Rare Isotope Beams.
The Compton Spectrometer and Imager (COSI) is a 0.2-5 MeV gamma-ray telescope designed for spectroscopy, imaging, and polarimetry of astrophysical sources. With its excellent energy resolution and localization capabilities, COSI is uniquely equipped to study signatures of electron-positron annihilation at the heart of the Milky Way Galaxy, radioactive decays from stellar and explosive nucleosynthesis, and has potential to serve as a key instrument for finding gamma-ray counterparts to multimessenger events, including neutron star mergers, high-energy neutrinos, and nearby supernovae. This presentation will motivate these scientific goals and explain how COSI, originally developed as a balloon-borne instrument, contributes to the understanding of each topic. Relevant results from COSI's 46-day balloon flight from 2016 serve as proof-of-concept for the upcoming iteration of COSI as a NASA Small Explorer satellite mission, slated for launch in 2026. The COSI satellite is expected to make great advancements in the MeV regime which will provide important constraints on astrophysical models of gamma-ray emission.
The $\beta$-decay of the free neutron contains a wealth of information about the charged weak interaction. Measurements of the lifetime and angular correlation coefficients can be use to determine $V_{ud}$, the first element of the Cabibbo–Kobayashi–Maskawa quark mixing matrix.Traditionally Super-allowed Fermi nuclear beta-decays have provided the most precise determination of $V_{ud}$, but modern neutron experiments are poised to generate results with similar or better precision. Having these two complementary determinations will provide a powerful tool to probe for physics beyond the standard model. The UCN$\tau$ experiment at the Los Alamos Ultracold Neutron facility has completed a $\approx 0.03$ % measurement of the neutron lifetime using a magneto-gravitational trap with {\it in situ} neutron detection, $\tau_n = 877.75(0.28)_{stat}(0.22)_{syst}$ s. Ultracold neutrons are stored for up to 5000~s and the surviving neutrons are counted to determine the decay lifetime. The trap eliminates material interactions during the storage period and its asymmetric shape is designed to remove super-barrier neutrons in stable orbits. As a cross check of the {\it in situ} counting method a recent measurement emptied the trap to an external detector after storage resulting in a value of $\tau_n = 877.1 (2.6)_{stat}(0.8)_{syst}$ s. Future upgrades are expected to push the precision of UCN$\tau$ to $\leq 0.1$ s. The results of these recent measurements and the path towards a 0.1~s precision on $\tau_n$ will be presented.
We report on the result of the neutron electric dipole moment EDM search which took data in 2015 and 2016 at PSIs ultracold neutron source. The neutron EDM is deemed to be one of the most sensitive probes of physics beyond the standard model. The experiment measured the precession frequency of spin polarized neutrons as a function of a strong electric field. The electric dipole moment of the neutrons leads to a linear dependence between those two quantities. After a blinded data analysis by two independent teams, we concluded that our results do not show this dependence within statistical uncertainties. We thus published a new upper limit of $d_n < 1.8\, 10^{-26}$ e cm [1]. The new result also significantly improves systematic uncertainties which will be discussed in detail. We will also give a future outlook on our new apparatus, n2EDM, which is currently set up at PSI.
[1] C. Abel et al. “Measurement of the Permanent Electric Dipole Moment of the Neutron” Phys. Rev. Lett. 124, 081803 (2020) 10.1103/PhysRevLett.124.081803.
The Dark Energy Survey (DES) is an optical astronomical imaging survey of one-quarter of the Southern sky. The on-sky operations for the survey were completed in 2019, with observations conducted over the course of 6 years with a 3-square-degree wide-field mosaic camera -- the Dark Energy Camera, or DECam -- installed on the Blanco 4-meter telescope at the Cerro Tololo Interamerican Observatory in the Chilean Andes. The primary scientific goal of the DES is to measure properties of the agent driving the acceleration of the Universe (“Dark Energy”) that was discovered over 20 years ago, but the data have also been useful for studies beyond its primary purpose. In this talk, I discuss DES instrumentation, DES operations, and current DES results.
Tests of Symmetries and the Electroweak Interaction
The permanent electric dipole moment of the neutron (nEDM) provides one of the most promising systems for searches of undiscovered CP-violations. The Standard Model (SM) provides a contribution to the nEDM several order of magnitudes smaller than the current experimental bound, thus the experimental finding of a permanent nEDM provides a unique, background-free window for potential discovery of physics Beyond the Standard Model (BSM).
Contributions to the nEDM can come from effective operators, describing at low hadronic energies the effects of BSM theories, and from the theta term of Quantum Chromodynamics (QCD). In order to interpret future experimental positive and null results for the nEDM, and disentangle the possible sources of CP-violation, we need to precisely determine the hadronic matrix elements of the corresponding renormalized operators.
The most promising tool to determine hadronic matrix elements is with a non-perturbative study of QCD on the lattice. I will briefly introduce lattice QCD together with the most recent developments, such as the gradient flow. I will then present and discuss the current status of lattice QCD calculations, including recent claims on the role of the theta term in electric dipole moment
calculations. Conclusions will summarize challenges and possibilities for near-future calculations.
One of the most interesting puzzles in physics is the baryon asymmetry of the universe (BAU). One requirement to explain the observed BAU is the violation of the combined charge conjugation (C) and parity (P) symmetries. While the Standard Model (SM) of particle physics contains sources of CP violation, it is too small to explain the BAU. In order to help reconcile theory and observation, additional sources of CP violation are needed. One of the most sensitive probes of CP violation is the neutron electric dipole moment (nEDM), for which the current upper limit is dn < 1.8 x 10-26 e-cm (90% CL). This talk will present the status of a new cryogenic apparatus under construction at the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) which aims to reduce the current upper limit by two orders of magnitude with a targeted sensitivity of dn < 3.0 x 10-28 e-cm.
This material is based upon work supported by the U.S. National Science Foundation under Grants No. 1812340 and 1822502.
The Los Alamos National Laboratory room-temperature neutron EDM (nEDM) experiment's goal is to measure the electric dipole moment (EDM) of the neutron with a projected uncertainty of $3 \times 10^{-27}$ e-cm. It will use Ramsey's method of separated oscillatory fields to track the spin precession of neutrons in two cells situated in a magnetically shielded room with precisely controlled and measured fields. Using two cells allows for the cancellation of common mode effects, reducing systematic uncertainties. Performed at the Los Alamos ultracold neutron (UCN) source, this experiment is one of several current nEDM experiments that search for a large permanent EDM because a permanent EDM is a CP-violating physical property. The Standard Model allows for only a small amount of CP-violation, too low to account for the matter-antimatter asymmetry of the universe. Experiments investigating CP-violation can probe physics beyond the Standard Model, including constraining the mass scale of new physics and investigating the mechanism of baryogenesis. This talk will cover the theoretical implications of an EDM, give an overview of the LANL nEDM experiment, and provide an update of its current status.
The TUCAN collaboration is installing a new ultracold-neutron source using a superfluid-helium converter driven by a spallation source at TRIUMF’s proton cyclotron. Its world-leading ultracold-neutron-production rate will allow us to search for a neutron electric dipole moment with a sensitivity of $10^{-27}$ e$\cdot$cm, an improvement by one order of magnitude over the currently best limit. Such an electric dipole moment would be direct evidence for a new CP-violating mechanism beyond the Standard Model of particle physics and could explain the matter-antimatter asymmetry in the universe.
This presentation will show our latest progress towards completing the source and our preparations for the electric dipole moment experiment.
Physics at High Energies
The study of the 125 GeV Higgs boson can open a window of sensitivity to a new dark sector. Results of searches for both prompt and non-prompt decays of the Higgs boson into new dark sector particles in 13 TeV pp collisions with the ATLAS detector are presented. Searches that encompass a wide range of new particle masses, lifetimes and degrees of collimation of decay products are discussed.
Many theories beyond the Standard Model predict new phenomena, such as heavy vectors or scalar, vector-like quarks, and leptoquarks in final states containing bottom or top quarks. Such final states offer great potential to reduce the Standard Model background, although with significant challenges in reconstructing and identifying the decay products and modelling the remaining background. The recent 13 TeV pp results, along with the associated improvements in identification techniques, will be reported.
Precision Physics at High Intensities
The production of cold antihydrogen atoms at CERN's Antiproton Decelerator (AD) has opened up the possibility to perform direct measurements of the Earth's gravitational acceleration on antimatter bodies. This is the main goal of the AEgIS collaboration: to measure the value of g using a pulsed source of cold horizontally travelling antihydrogen via a moiré deflectometer/Talbot-Lau interferometer. The first milestone of pulsed production of antihydrogen [1] using a resonant charge-exchange reaction between cold trapped antiprotons and Rydberg positronium (or Ps, the atomic bound state of a positron and an electron) atoms is presented. The outlook in enhancing the intensity of the pulsed antihydrogen source thanks to the 100 keV ELENA decelerator antiproton beam is presented, with a view to first gravitational experiments using a pulsed beam of antihydrogen.
Further physics directions under development in AEgIS encompassing also nuclear physics, and relying on similar pulsed interactions between antiprotons and Rydberg atoms, will also be discussed.
[1] C. Amsler et al. (The AEgIS collaboration), Pulsed production of antihydrogen, Commun. Phys. 4, 19 (2021) https://doi.org/10.1038/s42005-020-00494-z
The ALPHA experiment has conducted the highest precision measurements on antihydrogen to date in order to test matter / antimatter symmetries. Our recent demonstration of laser cooling antihydrogen represented not only a novel spectroscopic survey in the antiatom, but also an important technical milestone in improving our comparisons against hydrogen [1]. A cooled population of antihydrogen atoms offers a new avenue in pursuit of antihydrogen spectroscopy competitive with the best measurements in hydrogen, and will be critical to performing precision gravity measurements [2]. We present a summary of spectroscopy measurements in ALPHA to date, and discuss our developments and prospects for future measurements of the antihydrogen spectrum, as well as our efforts towards performing the first gravitation measurements on antimatter with ALPHA-g.
[1] Baker, C.J., et al. Laser cooling of antihydrogen atoms. Nature 592, 35–42 (2021)
[2] Bertsche W. A. Prospects for comparison of matter and antimatter gravitation with ALPHA-g. Phil. Trans. R. Soc. A. 37620170265 (2018)
Two critical questions in particle physics remain unanswered--what is the particle nature of dark matter, and why is there no antimatter in the universe? Searches for neutron oscillations are an essential component of the worldwide program to understand baryon number violation and what comprises dark matter, but are underexplored experimentally. If dark matter is made up of a rich hidden sector such as "mirror matter," a neutral particle such as the neutron might transform into its sterile twin. The HIBEAM (High Intensity Baryon Extraction and Measurement) program at the European Spallation Source will search for neutrons disappearing into mirror neutrons and the possibility that they regenerate back into either neutrons or antineutrons. This program will inform a future high sensitivity search for free neutrons transforming directly into antineutrons as part of the NNBAR experiment, which can improve sensitivity by three orders of magnitude over the previous direct search.
Neutron-antineutron oscillations and proton decay are long-sought manifestations particle unification models. At least one of these phenomena is expected to exist due to the observed baryon asymmetry of the Universe. Constraints on unification and beyond-standard models from existing and newly proposed experiments depend heavily on nucleon and nuclear matrix elements of quark-level BNV operators. These amplitudes are determined by nonperturbative QCD dynamics and must be computed numerically to avoid nucleon model uncertainties. Within the past few years, these amplitudes have been computed on a lattice with tight control over most sources of systematic effects. I will present results and discuss implications of these calculations for neutron-antineutron oscillations and proton decays.
Nuclear Forces and Structure, NN Correlations, and Medium Effects
The strong interaction between nucleons has been at the heart of nuclear physics since the very beginning of this field. Remarkable progress has been achieved in recent decades towards quantitative understanding of nuclear forces and currents in the framework of chiral effective field theory. Combined with ab-initio few-body methods, this approach opens the way for a systematically improvable and model independent description of light nuclei and low-energy nuclear reactions in harmony with the symmetries of QCD. I will review the current status of nuclear chiral EFT,
highlight selected applications and discuss prospects for the near future.
The instability of hyperons against the weak interaction hinders the experimental extraction of baryon-baryon low-energy observables in the strange sector. In this energy regime, a reliable numerical procedure to obtain information of nuclear physics quantities is lattice QCD, a high-demanding numerical approach to solve the complex dynamics of strongly-interacting systems directly from the degrees of freedom of the Standard Model, quarks and gluons. In this talk, I will present the results obtained by the NPLQCD collaboration, constraining the coefficients from the relevant effective field theories of two non-relativistic baryons, as well as the results from a variational calculation using a large interpolating operator set. I will also show the first steps taken to study these systems using quantum computers.
Parton and Gluon Distributions in Nucleons and Nuclei
Generalized parton distributions (GPDs) encompass crucial information on the three-dimensional structure of hadrons and their mechanical properties via the energy-momentum tensor form factors. I will present our improved understanding of the extraction of GPDs from hard exclusive measurements, as well as the modelling efforts undertaken to give a more comprehensive picture of extraction uncertainties. I will also discuss the implementation of theoretical constraints, with a particular focus on the situation at low Bjorken x which is relevant in collider kinematics like the future EIC.
The study of the internal dynamics of nucleons, which make up the majority of visible matter in the universe, is critical to our understanding of the theory of strong interactions and the nature of matter itself. The recently upgraded CEBAF Large Acceptance Spectrometer (CLAS12) at Jefferson Lab aims to study questions such as: how are quarks confined in nuclear matter, how do the properties of protons and neutrons emerge from their constituent quarks and gluons and how do the nuclear forces arise from basic interactions? In order to answer these questions, CLAS12 began taking data in Spring 2018 with an 11 GeV longitudinally polarized electron beam incident on a liquid hydrogen target. In this talk I will cover some of the early results from CLAS12 that are already making valuable contributions to our understanding of the role of individual quarks and gluons in nucleonic structure and hadronization in general. These results include several measurements sensitive to Transverse Momentum Dependent distributions (TMDs) or Generalized Parton Distributions (GPDs) which cover the distribution of partons in 3D momentum and coordinate space respectively and are only the first step in CLAS12's contributions to the understanding of the nature of matter itself.
Recent years have brought a breakthrough in calculations of the x-dependence of partonic distributions on a Euclidean lattice. In this talk, I will discuss our progress in extracting generalized parton distributions (GPDs) from the quasi-distribution approach. I will present both the leading-twist GPDs and our exploratory studies of selected twist-3 cases.
A new era for the exploration of hadron structure has begun with the Jefferson Lab 12 GeV program and the planned Electron Ion Collider. The new generation of experiments will allow us to probe the quantum correlation function (QCFs) of quarks and gluons that emerges from the theory of strong interactions. Since these QCFs are not direct physical observables, the experimental data needs to be analyzed within the framework of QCD factorization that stress test in a self consistent manner the predictive power of QCD and the universality of QCFs using Bayesian inference. In this talk we will discuss recent progress on theory and phenomenology in the exploration of nucleon’s spin structures.
Particle and Nuclear Astrophysics
Recent experimental and theoretical nuclear physics results that connect to Big Bang Nucleosynthesis (BBN) will be reviewed. Motivations for new nuclear physics measurements are provided by precise astrophysical deuterium observations and the need to understand the BBN production of elements heavier than helium. These heavier elements (lithium, beryllium, boron, carbon, nitrogen, etc...) may be important seed material for further nucleosynthesis in the first generation of stars. Specific cases where new measurements are needed will be indicated.
Neutrons play a dominant role in the stellar nucleosynthesis of heavy elements. We review a scheme for the experimental determinations of neutron-induced reaction cross sections using a high-intensity neutron source based on the 18O(p,n)18F reaction with an 18O-water target at SARAF’s upcoming Phase II. The quasi-Maxwellian neutron spectrum with effective thermal energy kT ≈ 5 keV, characteristic of the target (p,n) yield at proton energy Ep ≈ 2.6 MeV close to its neutron threshold, is well suited for laboratory measurements of MACS of neutron-capture reactions, based on activation of targets of astrophysical interest along the s-process path. 18O-water’s vapour pressure requires a separation in between the accelerator vacuum and the target chamber. The high-intensity proton beam (in the mA range) of SARAF is incompatible with a solid window in the beam’s path. Our suggested solution is the use of a Plasma Window, which is a device that utilizes ionized gas as an interface between vacuum and atmosphere, and is useful for a plethora of applications in science, engineering and medicine. The high power dissipation (few kW) at the target is expected to result in one of the most intense sources of neutrons available at stellar-like energies. Preliminary results concerning proton beam energy loss and heat deposition profiles for target characteristics and design, a new full-scale 3-dimensional computer-aided design model of the Plasma Window (as well as its operation principles) and the planned experimental scheme, will be reviewed.
Time-dependent magnetic fields can be sourced by spinning neutron stars, orbiting binaries and merging neutron stars. We consider electromagnetic radiation from
axion condensates in the background of an alternating magnetic field. We find that a resonant peak in radiation can occur when the frequency of the alternating magnetic field is comparable with the axion mass scale. More interestingly, in situations where the frequency of the alternating magnetic field itself changes with time, as can be the case in binary mergers due to a steady increase in orbital frequency, the resonant peak in radiation may occur for a range of axion mass scales scanned by the time-varying magnetic field frequency. radiation may occur for a range of axion mass scales scanned by the time-varying magnetic field frequency.
Cosmic Physics and Dark Energy, Inflation, and Strong-Field Gravity
In this talk, I will discuss our recent analysis of the BOSS power spectrum monopole and quadrupole, and the bispectrum monopole and quadrupole data, using the predictions from the Effective Field Theory of Large-Scale Structure (EFTofLSS). Specifically, we use the one-loop prediction for the power spectrum and the bispectrum monopole, and the tree level for the bispectrum quadrupole. After validating our pipeline against numerical simulations as well as checking for several internal consistencies, we apply it to the observational data. We find that analyzing the bispectrum monopole to higher wavenumbers thanks to the one-loop prediction, as well as the addition of the tree-level quadrupole, significantly reduces the error bars with respect to our original analysis of the power spectrum at one loop and bispectrum monopole at tree level. We find significant error bar reduction with respect to the power spectrum-only analysis.
Remarkably, the results are compatible with the ones obtained with a power-spectrum-only analysis, showing the power of the EFTofLSS in simultaneously predicting several observables. We find no tension with Planck.
In the standard cosmological paradigm, the initial condition follows Gaussian statistics. At later times, gravitational evolution induces nonlinearities in the large-scale structure, and information that had been fully captured by the two-point statistics gets spread into higher-order statistics. In this talk, I will present our recent progress on the N-point Correlation Function (NPCF) for N up to 6, including an analytic formalism for the Gaussian covariance matrix and the first detection of the 4PCF due to nonlinear structure formation. Finally, I will discuss our recent analysis of parity-odd modes of the 4PCF using the data from the Baryon Oscillation Spectroscopic Survey (BOSS).
Recently we have shown that the galaxy 4-point correlation function, which measures an excess of quartets of galaxies over random, is sensitive to parity violation in our universe’s large scale structure. It is fundamentally 3d and thus has a handedness even after applying isotropy, in contrast to galaxy pair and triplet correlations. With this new observable we have detected parity violation at high statistical significance using the largest currently available sample, the SDSS Baryon Oscillation Spectroscopic Survey’s roughly 1 M galaxies. If confirmed by upcoming sky surveys such as DESI this would indicate new physics operant in the universe’s earliest moments. In this talk I will discuss this result and the many systematics tests performed to test its robustness, as well as prospects for the future
Tests of Symmetries and the Electroweak Interaction
Experimental tests of fundamental symmetries using nuclei and other particles subject to the strong nuclear force have led to the discovery of parity (P) violation and the discovery of charge-parity (CP) violation. It is believed that additional sources of CP-violation may be needed to explain the apparent scarcity of antimatter in the observable universe. A particularly sensitive and unambiguous signature of both time-reversal- (T) and CP-violation would be the existence of an electric dipole moment (EDM). The next generation of EDM searches in a variety of complimentary systems will have unprecedented sensitivity to physics beyond the Standard Model. My talk will focus on certain rare diamagnetic atoms which have pear-shaped nuclei. This uncommon nuclear structure significantly amplifies the observable effect of T, P, & CP-violation originating within the nuclear medium when compared to isotopes with nearly spherical nuclei such as Mercury-199. Certain isotopes of Radium (Ra) and Protactinium (Pa) are both expected to have enhanced atomic EDMs and will be produced in abundance at the Facility for Rare Isotope Beams currently under construction at Michigan State University. I will describe the current status of ongoing searches and the prospects for next generation searches for time-reversal violation in the FRIB-era.
The neutron represents a versatile tool in the realm of fundamental particle physics. It is used to perform precision physics measurements at low energies with the goal to search for signals beyond the Standard Model of particle physics. In this respect, the neutron Electric Dipole Moment (EDM) has attracted interest as a promising channel for finding new physics since decades. The existence of a permanent neutron EDM violates the combined symmetries of parity (P) and charge conjugation (C) invoking the CPT symmetry. This new source of CP violation could help to explain the apparent baryon asymmetry in our Universe. The Beam EDM experiment aims to measure the neutron EDM using a novel technique. The experiment exploits a time-of-flight Ramsey technique with a pulsed beam which allows to distinguish between time-dependent and time-independent effects – and by this overcoming the previously limiting systematic relativistic vxE-effect. Recently, a proof-of-principle apparatus has been developed to perform detailed systematic investigations for a future full-scale experiment intended for the European Spallation Source in Sweden. In this presentation, the details of the experimental apparatus, future prospects, together with the latest results from a data taking campaign at the Institute Laue-Langevin in France will be presented.
A non-zero electric dipole moment (EDM) of a fundamental particle or a composite system, such as a nuclei, an atom, or a molecule, violates the time reversal symmetry, implying a violation of the combined charge conjugation and parity (CP) symmetry. The $^{199}$Hg EDM experiment has the most precise measurement on the frequency difference leading to an upper limit on the $^{199}$Hg EDM $\mid d_{Hg}\mid < 7.4 \times$ $10^{-30}$ e$\cdot$cm (95$\%$ C.L.) in 2016 without an internal electric field enhancement; it has provided a stringent constraint on new sources of CP violation beyond the Standard Model. This talk will describe the state-of-art techniques to instrument a set of mercury vapor cells, including the laser system to optically polarize and detect the spin-dependent interactions. $^{199}$Hg atoms are also applied in the neutron EDM experiment at Los Alamos National Laboratory. It is implemented both as the co-magnetometer, like the neutron EDM search at Paul Scherrer Institute (PSI), and as an external magnetometer inside the high voltage electrode to monitor the temporal fluctuation of the magnetic field background. I will describe the details of using $^{199}$Hg in both experiments.
This work is supported by the National Science Foundation, grant PHY-1828512.
One of the motivations to search for new physics Beyond the Standard Model (BSM) is to understand the baryon asymmetry present in the Universe, namely the discrepancy between the theoretical prediction of the baryon asymmetry based on the SM and the value obtained through observations of the cosmic microwave background. The Neutron OPtics Time Reversal EXperiment (NOPTREX) Collaboration seeks to measure signatures of parity-odd (P-odd) and time-reversal-symmetry-odd (T-odd) interactions in polarized neutron transmission through polarized nuclear targets which contain p-wave resonances in the eV energy range. This can be done through the use of neutron transmission resonance spectroscopy. The relative strength of the weak and strong coupling constants is known to be ~10-7; however, the many-body nature of a resonant compound nuclear system results in amplification effects specific to the weak interaction which can increase the discovery potential for such a measurement by a factor of 105-106, making this an attractive system in which to study T-violation. Recent theoretical work has also suggested that the NOPTREX measurement may be sensitive to P-even/T-odd interactions; placing limits on such an interaction will be useful to understand the underlying electroweak interactions between nucleons that can result in a T-symmetry violating signal. This talk will outline the status of our work on the neutron-nucleus resonance spectroscopy techniques needed to quantify the sensitivity of the NOPTREX measurement to the P-odd/T-odd signals as well as a summary of the possible P-even/T-odd limits NOPTREX may be able to achieve.
Physics at High Energies
Many theories beyond the Standard Model predict new phenomena, such as $Z'$, $W'$ bosons, or heavy leptons, in final states with isolated, high-pt leptons (e/mu/tau). Searches for new physics with such signatures, produced either resonantly or non-resonantly, are performed using the ATLAS experiment at the LHC. This includes a novel search that exploits the lepton-charge asymmetry in events with an electron and muon pair. Lepton flavor violation (LFV) is a striking signature of potential beyond the Standard Model physics. The search for LFV with the ATLAS detector focuses on the decay of the Z boson into different flavour leptons (e/mu/tau). The recent 13 TeV pp results will be reported.
Many new physics models predict the existence of Higgs-like particles decaying into two bosons (W, Z, photon, or Higgs bosons) making these important signatures in the search for new physics. Searches for Vy, VV, and VH resonances have been performed in various final states. In some of these searches, jet substructure techniques are used to disentangle the hadronic decay products in highly boosted configurations. This talk summarises recent ATLAS searches with Run 2 data collected at the LHC and explains the experimental methods used, including vector- and Higgs-boson-tagging techniques.
Precision Physics at High Intensities
The constituents of dark matter are still unknown, and the viable possibilities span a very large mass range. Specific scenarios for a thermal origin of dark matter sharpen this mass range to within about an MeV to 100 TeV. Most of the stable constituents of known matter have masses in the MeV to GeV range, and a thermal origin for dark matter works in a simple and predictive manner in this mass range as well, yet it remains largely unexplored. Two complementary fixed target experiments that use a primary electron beam and have unique sensitivity to models of light DM in the this mass range are the Heavy Photon Search (HPS) at Jefferson Lab and the planned Light Dark Matter eXperiment (LDMX) at SLAC. HPS searches for visibly decaying dark photons through two distinct methods - a resonance search in the e+e- invariant mass distribution and a displaced vertex search for long-lived dark photons. LDMX searches for invisibly decaying dark photons through a missing-momentum experiment. This contribution will give an overview of the theoretical motivation, the main experimental challenges on LDMX and HPS and how they are addressed, the projected sensitivities in comparison to other experiments, and preliminary results of the HPS displaced vertex search for the 2016 Engineering Run.
Elucidating the nature of dark matter remains a central challenge in fundamental physics. A growing interest in light (sub-GeV) dark matter consisting of new particles coupling only feebly to ordinary matter has recently emerged. Low-energy, high luminosity colliders such as BABAR are ideally suited to probe these possibilities. In this talk, we will review searches for dark sectors and light dark matter performed at BABAR. These measurements demonstrate the importance of B-factories in fully exploring dark matter and light BSM physics.
Nuclear Forces and Structure, NN Correlations, and Medium Effects
Recent years have seen enormous progress in ab initio approaches to the nuclear many-body problem, ranging from traditional coordinate and configuration-space methods to Lattice Effective Field Theory (EFT). EFT and renormalization group (RG) techniques have provided new systematic tools to treat the correlations in strongly interacting systems, and to inject ab initio ideas into methods that previously relied on empirical interactions.
As a result, we have seen ab initio forays into the domain of heavy nuclei, including first converged calculations of Pb-208 with two- and three-nucleon interactions from chiral EFT, the generation of mass tables for regions of the nuclear chart, electroweak transitions of interest for fundamental symmetry programs, and some of the most important nuclear interactions in nature.
I will discuss these and selected additional highlights, before looking ahead at the next round of challenges in improving the accuracy and expanding the reach of ab initio methods to deformed and more exotic nuclei. I will also touch upon ideas to tackle these challenges.
Many progresses have been made in developing nuclear Hamiltonians within the framework of chiral effective field theory. In particular, the develop of chiral interactions that are fully local opened the way of implementing these Hamiltonians in Quantum Monte Carlo calculations. The advantage of using Quantum Monte Carlo methods is that they are not limited to use soft interactions, and calculations dedicated to explore the role of cutoffs can be done.
I will devote this talk to discuss several new results for nuclei up to A=16, and addressing several questions regarding the prediction power of these Hamiltonians, and issues related to regulators and cutoffs. I will show nuclear properties including energies, radii, form factors, and others.
I will then discuss properties of nuclear matter using the same Hamiltonians.
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Neutron stars are cosmic laboratories uniquely poised to determine the nuclear equation of state (EOS). The historical detection of the binary neutron star merger GW170817 by the LIGO-Virgo collaboration and other critical observations since then are providing new insights into the nature of neutron-rich matter. In turn, the recent extraction of the neutron skin thickness of 208Pb by the PREX collaboration seems to suggest that the EOS in the vicinity of nuclear matter saturation density is stiff. This creates some tension with the tidal deformability of a 1.4 Msun neutron star reported by the LIGO-Virgo collaboration that suggests that the EOS at slighter higher densities is soft. If confirmed, this situation may provide evidence in favor of a phase transition in the interior of neutron stars.
The development of radioactive ion beams (RIB) in the mid-eighties has enabled the exploration of regions of the nuclear landscape away from the valley of stability, uncovering nuclei with unexpected features. Halo nuclei exhibit among the most peculiar structures in the nuclear landscape. Unlike most nuclei, they have a very large matter radius compared to their isobars, that can be explained by the presence of one or two loosely-bound nucleons away from the others, forming a diffuse halo around a compact core. These clusterized objects have therefore challenged the usual picture of a nucleus as a compact object. Due to their short life-time, exotic nuclei are often studied through reactions, in which they collide with a target. Various kinds of reactions, e.g. transfer, breakup or one-neutron knockout, are studied at RIB, such as FRIB. The latter corresponds to the removal of one or two valence nucleons from the projectile on a light target. It is often favored for low-intensity beams, because, thanks to the fragile nature of halo nuclei, it exhibits a high cross section. In this talk, I will show how effective field theory descriptions of halo projectiles integrated within a few-body reaction formalism efficiently bridge ab initio predictions and one- neutron knockout observables. The comparison of the predicted cross sections with experimental data therefore provides a stringent test for these state-of-the-art nuclear structure models. I will then present a sensitivity analysis of one-neutron knockout cross sections of more deeply-bound neutron-rich nuclei to their neutron distributions, indicating that these observables could be used to extract information about their neutron skin thickness.
Neutrino Masses and Neutrino Mixing
In this talk, I will describe neutrino interactions over a wide energy range and overview experimentally observed reactions. I will discuss theoretical approaches for the evaluation of scattering cross sections for different neutrino-induced processes at various energy scales. The energy range and precision of modern and future neutrino experiments and observations require us to account for radiative corrections and improve phenomenological input in reactions with neutrinos. I will motivate and discuss a few recent precise calculations of radiative corrections to charged-current and neutral-current neutrino scattering processes and discuss phenomenological applications of such calculations.
NOvA is a long-baseline neutrino experiment at Fermilab that studies neutrino oscillations via electron neutrino appearance and muon neutrino disappearance. The oscillation measurements compare the Far Detector data to an oscillated prediction which combines Near Detector (ND) data and the current understanding of neutrino interactions through simulation using GENIE. By adjusting the cross section model to better represent neutrino scattering data from NOvA’s ND and other experiments, we can extract oscillation parameters with more accurate cross section uncertainties. The adjustments are performed using the ND data and simulation, before oscillations occur. We describe the tuning made to GENIE, particularly to the 2p2h and FSI models, and the construction of the associated uncertainties.
Neutrino-nucleus cross sections are an important facet of interpreting results in accelerator neutrino experiments. However, these cross sections are still not theoretically well understood. I will discuss how near detector tunes, widely adopted in accelerator neutrino experiments to address cross section uncertainties, affect new physics searches. I will present two illustrative new physics scenarios, light sterile neutrinos and missing energy signatures, present the relevant observable spectra before and after tune, and discuss the prospects of identifying new physics.
Sensitivities of future large underground neutrino oscillation experiments are critically dependent upon precisely understanding the initial energy of an incoming neutrino via cross section models and event generator predictions which summarize prospective final states. Extracting the true initial energy of the neutrino is thus model dependent, requiring a deep understanding of the biases present within the community's generators and various reconstruction paradigms. The Electrons-for-Neutrinos ($e4\nu$) and Muons-for-Neutrinos ($\mu4\nu$) Initiatives aim to constrain both of these issues by studying the light charged leptonic cousins of the neutrino, exploiting universal vector-like interactions to better understand underlying systematic modeling uncertainties, improve neutrino cross sections models, and calibrate reconstruction techniques \textit{in situ}. e4ν has recently taken new electron scattering data on ${}^{12}$C, ${}^{40}$Ar, and many other nuclei using the CLAS12 detector in Hall B at Thomas Jefferson National Accelerator Laboratory, and plans to release many relevant measurements for the neutrino community in the coming years. $\mu4\nu$ is a burgeoning concept, and currently works within the MicroBooNE Collaboration at Fermilab to study cosmic muon scattering topologies relevant for testing energy reconstruction techniques in calorimetric experiments such as future flagship experiments like DUNE. Each of these programs will be discussed, and recent work will be shown.
Standard Model predictions of neutrino-nucleus scattering cross sections for neutrino energies around 1 GeV or more are needed to precisely extract neutrino oscillation parameters from future neutrino oscillation experiments such as DUNE and Hyper-Kamiokande. However, theoretical predictions are challenging due to non-perturbative physics arising from low-energy QCD interactions in nuclear systems. In this talk, I will show how lattice QCD results could be used to constrain non-perturbative physics of Standard Model. In particular, I will focus on calculations of the nucleon form factors relevant to the quasi-elastic processes and their impacts to the cross section predictions.
Complete Monte Carlo simulation of a neutrino experiment typically involves the lengthy and CPU-intensive process of integrating models of incoming neutrino fluxes, event generation, as well as detector setup, of which accounting for the detector response in an essential component.
We provide an alternative, fast, geometry-independent system for modeling the energy smearing and angular smearing involved in detector responses we referentially term NuSmear. We discuss NuSmear’s generic parameterized smearing capabilities as a software system directly integrated into the GENIE event generator, and explain its incorporation of model-based resolution functions for individual particle types, particularly those derived from the DUNE Conceptual Design Report (CDR). We go on to demonstrate the functionality of NuSmear in dealing with further smearing dependencies, such as variable chances of observation for neutrons, as well as differences between exiting and contained particle tracks when dealing with muons and pions. Lastly, we conclude by exploring the potential for future user-customized modeling in NuSmear, down to the level of tailored smearing distributions for chosen individual particle parameters.
The Baksan Experiment on Sterile Transitions (BEST) was designed to investigate the deficit of electron neutrinos, $\nu_e$, observed in previous gallium-based radiochemical measurements with high intensity neutrino sources, commonly referred to as the gallium anomaly. The BEST setup is comprised of two zones of liquid Ga target to explore neutrino oscillations on the meter scale. Any deficits in the $^{71}$Ge production rates in the two zones, as well as the differences between them, would be an indication of nonstandard neutrino properties at this short scale. The target was exposed to $^{51}$Cr neutrino source and extractions $^{71}$Ge extractions from the two Ga targets were made. The $^{71}$Ge decay rates were measured and 4σ deviations from unity were observed for the ratio of the measured to the predicted rate from the known cross section in both zones.
I will discuss in my talk these recent results from BEST and how they reaffirm the previously observed Gallium anomaly. I will present how they fit into the landscape of other recent results that give hints of new physics at short baselines, but also show what could be possible explanations besides sterile neutrinos.
Neutron stars are unique laboratories for studying strongly interacting, neutron-rich matter under extreme conditions. While much has already been learned about neutron stars in the era of multi-messenger astronomy, many key questions remain, especially regarding the composition and equation of state (EOS) of the ultra-compressed matter in their inner cores. At the same time, chiral effective field theory (EFT) has developed into a powerful framework to study nuclear matter properties with quantified uncertainties in the moderate-density regime for modeling neutron stars.
In this talk, I will discuss recent developments in EFT-based nuclear matter calculations and their implications for the structure of neutron stars. I will also show how EFT enables statistically robust comparisons among competing nuclear theory predictions, nuclear experiments, and observational constraints on the EOS.
The density dependence of the symmetry energy is a quantity that has long been anticipated to inform the determination of the neutron matter equation of state (EOS). Knowledge of the neutron distribution in heavy nuclei impacts nuclear structure theory, our understanding of neutron star structure, nuclear spectroscopy, atomic parity measurements and more. Electron scattering has already proven to be powerful tool for determining the sizes of nuclei by measuring the electric charge distribution. It provides a clean probe of the nucleus that does not interact via the strong force. Parity-violating electron scattering (PVES) is a technique that exploits the fact that the weak force violates parity while the electromagnetic force is parity-conserving. In order to form the parity-violating asymmetry that allows us to isolate the weak term in the scattering cross-section, we employ a longitudinally polarized electron beam, with rapidly flipping helicity. The state-of-the-art Thomas Jefferson National Accelerator Facility in Newport News, Virginia, USA is able to produce the required highly polarized, high current, stable electron beam to perform such measurements. In this talk I will give an overview of the recently completed PREX and CREX experiments, present the results, and discuss some of the implications of the measurements.
Tests of Symmetries and the Electroweak Interaction
Neutron beta decay is an excellent case for testing the internal consistency of the Standard Model electroweak sector and probe new physics (NP) at the TeV scale through its absence of nuclear structure corrections. Radiative corrections (RC) precipitate the largest change to the decay rate and have received renewed interest due to recent changes. With the advent of precision lattice QCD calculations, a comparison with experimental form factors are intrinsically interesting for NP given that any differences due to RC are taken into account. Using chiral effective field theory, we report on percent-level unaccounted-for differences between the vector and axial weak charge with sizeable uncertainties. We discuss consequences for extracting NP from the comparison with lattice QCD and point towards successful future strategies.
The free neutron lifetime has been measured in two ways: by measuring the decay products of neutrons in a well calibrated neutron beam (beam experiment), or by counting the number of surviving neutrons stored in a UCN trap over time (bottle experiment). The lifetime results from the two different methods differ by 10 seconds, or five standard deviations. Recently, there has been a variety of experiments based on the “bottle method”, and these experiments have produced similar results with completely different treatments of the systematic errors. The average lifetime value extracted from the “beam” experiments is mainly from the Penning trap technique, and most of the statistics come from only a single experiment. One possible explanation for this large discrepancy is that one of the two methods has unaccounted systematic errors. The goal of the UCNProBe experiment is to measure the neutron lifetime to 1 second level using a novel “beam” technique with completely different systematic errors. In this talk, we will describe the experimental technique in detail and provide an update on the R&D progress on the experiment.
He6-CRES is a precision nuclear beta-decay experiment using the technique of cyclotron radiation emission spectroscopy (CRES) to preform beta-spectra measurements. We determine the energy of the beta by measuring the frequency of the cyclotron radiation when the beta decay occurs within a magnetic field. This aims to be a sensitive search for chirality-flipping interactions through the Fierz interference coefficient 'b'. This talk will introduce the He6-CRES experiment and present our first preliminary beta spectrum. I will also share insights we have gained on doing broadband CRES measurements of beta spectra spanning several MeV.
A precise determination of the pion electronic decay branching ratio $\Gamma(\pi\rightarrow e\bar{\nu}(\gamma))/\Gamma(\pi\rightarrow \mu \bar{\nu}(\gamma))$ provides the best test of electron-muon unversality, taken as valid in the Standard Model. Currently, the experimentally determined value of this ratio is lags behind the theoretical predicted value by an order of magnitude in precision. The PEN collaboration has performed detailed measurement of pion decays at the Paul Scherrer Institute with the goal of obtaining a relative uncertainty of $5\times 10^{-4}$ for the branching ratio of the $\pi^+\rightarrow \text{e}^\nu(\gamma)$ decay. The PEN apparatus detects pion decays at rest in the active target. The detector consists of active plastic scintillating beam counters, target, and hodoscope as well as charged particle tracking detectors and large solid angle pure CsI electromagnetic calorimeter. Among the key systematics are timing, particle tracking efficiencies, decays in flight, the acceptances, and the low-energy tail resulting from electromagnetic shower energy leakage out of the CsI calorimeter. A comprehensive review of the analysis to date including the relevant competing decay channels and systematics will be discussed.
Quark Matter and High Energy Heavy Ion Collisions
The ALICE experiment is dedicated to studying the properties of the quark-gluon plasma, a strongly-interacting matter produced in collisions of heavy-ions at the LHC. In this talk, recent highlights from ALICE in Pb+Pb collisions investigating the properties of the QGP will be shown, along with results from p+p and p+Pb collisions. Recently, ALICE has undergone a major upgrade in preparation for the LHC Run-3 heavy-ion program, which will also be presented.
Heavy ion collisions allow access to novel QCD and QED studies in a laboratory. The CMS heavy ion program is focusing on precision studies of the properties of quark-gluon plasma (QGP) and the strong electromagnetic fields, produced in such collisions at high energies. This talk will present recent CMS results on various QGP and QED probes, such as jets, electroweak bosons, heavy flavor hadrons, quarkonia, and leptons. A review of recent measurements of collective phenomena will also be presented.
The LHCb detector is a unique tool for studying heavy-ion collisions at the LHC. Because of its forward acceptance, the LHCb detector is able to study heavy ion collisions in kinematic regions complementary to those probed at other LHC and RHIC experiments. Furthermore, the LHCb detector's excellent momentum and vertex resolution make it an ideal tool for studying heavy-flavor production. In this talk, I'll present recent studies of heavy-ion collisions from the LHCb experiment.
Cumulants of conserved charge fluctuations probe the thermal state of
strongly interacting matter and have been the focus of many studies,
both theoretical and experimental, in recent years.
In lattice QCD calculations, they allow access to bulk thermodynamic
quantities at small, non-vanishing chemical potential via Taylor
expansion and find application in the search for a critical endpoint in
the QCD phase diagram. Furthermore, they can serve as benchmark
observables for constraining the range of validity of widely used hadron
resonance gas models.
Over the last years, the HotQCD collaboration has gathered high
statistics data on cumulants of conserved charge fluctuations from
lattice QCD simulations using the HISQ discretization scheme for
staggered fermions with 2+1 flavors. This talk aims to provide an
overview of recent results obtained using this data.
Specifically, precise continuum extrapolations for the six second order
cumulants of conserved charge fluctuations and their correlations are
presented and compared to various non-interacting, point-like hadron
resonance gas models. Furthermore, we present updated results on
pressure, energy density and entropy density calculations at non-zero
chemical potentials using up to 8th order Taylor expansions. We discuss
estimators of the radius of convergence for these expansions and
construct Padé approximants for the pressure at non-zero values of the
baryon chemical potential. We show that the pole structure of the Padé
approximants is consistent with not finding a critical endpoint for
temperatures above 135 MeV and $\mu_B/T \le 2.5$.
Nuclear Forces and Structure, NN Correlations, and Medium Effects
Much of what we know about high-energy components of nuclear structure comes from recent measurement campaigns at Jefferson Lab. Experiments from the 6 GeV era have provided precise results about short-range nucleon-nucleon correlations and their nuclear dependence. Additionally, an intriguing correlation was observed to measurements of modifications of nuclear quark distributions (EMC effect). I will highlight key insights gained from previous measurements (including recent ones) and present future experiments aimed at further illuminating these exotic components of nuclear structure.
Jefferson Lab measurements of the EMC effect in light nuclei demonstrated that the nuclear modification of quark parton distribution functions (pdfs) does not simply scale with the mass or density of the nucleus, as previously assumed, but is sensitive to microscopic details of the nuclear structure. In addition, it showed that the connection between the EMC effect and the presence of short-range correlations (SRCs) is more than just a consequence of both effects scaling with nuclear density. I will show new measurements of the isoscalar EMC effect for A=3 nuclei, taken by combining measurements of the 3H and 3He EMC effect, as well as the first measurement on 10B and 11B, which will expand the set of measurements in light nuclei where detailed ab initio calculations can be performed. In addition to comparing the observed EMC effect to calculations, I will also discuss the potential implications of these data in better quantifying the EMC-SRC correlation when combined with SRC measurements on the same nuclei. Finally, I will discuss experiments that will run later this year to include additional light nuclei, and also to try and separate A and isospin dependence of the EMC effect (and SRCs) in medium-to-heavy nuclei.
Understanding the modification of quarks in nucleons within nuclei (EMC effect) is a longstanding open question in nuclear physics. Recent experimental results from electron scattering at Jefferson Lab strengthen the correlation between the EMC effect and short-range correlated pairs (SRC) of nucleons in nuclei. That means that the EMC effect is probably driven by the high-momentum highly-virtual nucleons of the SRC pairs. This connection can be tested experimentally by measuring electron deep inelastic scattering from a nucleon and detecting its correlated SRC partner nucleon (tagging). This allows us to measure the quark modification of high-momentum nucleons.
In my talk, I will present preliminary results from a tagged experiment on deuterium at Jefferson Lab where the modification of protons were measured by tagging the recoiling neutrons.
Neutrino Masses and Neutrino Mixing
The discovery of neutrino oscillations has motivated the extension of the Standard Model and various neutrino experiments including beam-based neutrino facilities are expected to measure the related parameters more precisely, deepening our understanding of the nature of neutrinos. Beyond the neutrino-sector physics, such neutrino facilities are receiving increasing attention as they can test various new physics models and scenarios. I will overview what kind of new physics scenarios can be tested and how the new particles associated with them can be produced and detected, especially in the beam-based neutrino experiments.
The BeEST (Beryllium Electron capture in Superconducting Tunnel junctions) experiment searches for physics beyond the standard model (BSM) in the neutrino sector through momentum conservation in electron capture decay (EC) of Be-7 [1]. Be-7 atoms are directly implanted into Ta-based superconducting tunnel junction (STJ) sensors that can measure the energy of the recoiling Li-7 daughters with a few-eV precision. Sterile neutrinos in the keV mass range would reduce the recoil energy add a spectrum at lower energy whose shift depends on the neutrino mass and whose amplitude depends on |Ue4|2. We have measured a high-statistics Li-7 recoil spectrum with a single STJ pixel for 30 days at a low rate of 10 counts/s and excluded sterile neutrino mixing for |Ue4|^2 > 0.0002 at 90% confidence level in the 100 keV mass region [1]. This is an order of magnitude better than results from previous experiments. Surprisingly, the Li recoil spectra are broadened beyond the STJ detector resolution of ~2 eV FWHM. We have therefore started an effort to precisely model the electron energies for Li in different sites of the bcc Ta lattice of the STJ detector. We have also started to develop Al-based STJ detectors to distinguish BSM physics from known effects. In the full-scale BeEST experiment, the statistical precision to the sterile neutrino mixing |Ue4|^2 will approach O(1e-7) levels with increased number of pixels and a higher dose of 7Be. We will present our experimental approach, analytical methods, recent progress and projected experimental sensitivities.
The MicroBooNE collaboration recently released a series of measurements aimed at investigating the nature of the excess of low-energy electromagnetic shower events observed by the MiniBooNE collaboration. In this talk, we will present the latest results from both a search of single photons in MicroBooNE, as well as a series of three independent analyses leveraging different reconstruction paradigms which look for an anomalous excess of electron neutrino events. We additionally will highlight new results that use these well-understood selections to perform a search for an eV scale sterile neutrino in the 3+1 oscillation framework. Constraints are presented for regions of sterile neutrino oscillation parameter space relevant to the Gallium/Reactor $\nu_e$ disappearance anomaly and LSND/MiniBooNE $\nu_e$ appearance anomalies.
This talk will cover some recent progress on simulating and constraining MeV-scale heavy neutral leptons at neutrino experiments. I will introduce DarkNews, a fast simulation tool for generating dilepton and single photon events in accelerator neutrino experiments, and present new limits derived from the T2K near detector using a novel method to sample multi-dimensional parameter spaces.
Nuclear reactors are one of the major sources that have been used to study neutrinos. Reines and Cowan first detected neutrinos from Savannah River P Reactor. Later the KamLAND experiment observed neutrino oscillation and measured the oscillation parameter $\Delta m_{12} ^2$. The Daya Bay experiment precisely measured the mixing angle $\theta_{13}$ which was verified independently by Reno and Double-Chooz. Currently several short range reactor neutrino experiments are setting limits for sterile neutrino oscillations. Further, there is an ongoing effort to develop applications of neutrinos for nuclear reactor safeguard instrumentation and non-proliferation. This talk will give a brief overview of reactor neutrino experiments and the possible applications.
In this talk I will present the recent results on inclusive and exclusive electron scattering cross section measurements on Ar at Jefferson Lab Hall A. I will describe how this experiment will inform the future neutrino oscillation experiment like DUNE and I will describe how the electron scattering data can be used to determine accurate nuclear model that describes neutrino-nucleus interaction. High accuracy in understanding neutrino nucleus scattering is crucial for future long baseline neutrino experiments.
Parton and Gluon Distributions in Nucleons and Nuclei
Some Hard exclusive processes off thenucleon, involving the exchange of at least one high virtualityphoton off a quark, enable access to the transverse partonic structureversus the longitudinal momentum of the partons. The so-called Generalized Parton Distributions (GPDs), parametrizing theseprocesses, contain this information. Their interpretation can lead totomographic views of the partonic structure, a new way to access thespin repartitions and correlations among the partonic constituents...Jefferson Lab Hall A and C have been very successful over the lastcouple of years in measuring reactions, such as DVCS, enabling the extraction of GPDs and constraining GPD models. In this talk, we willdiscuss past results from JLab and what we learned out of them, aswell near future experiments, including new measurements, such as Timelike Compton Scattering, Hard Exclusive Meson Production, andpotential projects, such as Double Deeply Virtual Compton Scattering. We will discuss how the JLab Hall A/C GPD program is broadening the perspectives in GPD's related research in the valence quark region.
The Relativistic Heavy Ion Collider (RHIC) is the first and only collider in the world that is able to run polarized proton beams, allowing for polarized measurements at higher energies compared to fixed target experiments. Longitudinally polarized collisions probe the spin structure of the proton, while transversely polarized collisions allow for spin-momentum correlation measurements that are sensitive to both initial- and final-state effects. This talk will cover new results from the RHIC spin program including constraints to how much the gluon contributes to the spin of the proton and nuclear effects in spin-momentum correlations, as well as future opportunities with the STAR forward upgrade and the upcoming sPHENIX experiment. The spin program at the RHIC will continue to be an integral part in expanding our knowledge of the structure of the nucleon and will inform future measurements at the upcoming Electron-Ion Collider.
The virtual photon asymmetry $A_1$ is one of the fundamental quantities that provide information on the spin structure of the nucleon. The value of $A_1$ at high $x_{Bj}$ is of particular interest because valence quarks dominate in this region, which makes it a relatively clean region to study the nucleon structure. Several theoretical calculations, including naive SU(6) quark model, relativistic constituent quark model (RCQM), perturbative QCD (pQCD), predicted the behavior for $A_1$ and the quark polarization in the high $x_{Bj}$ valence quark region. The $A_1^n$ experiment during the 6 GeV JLab era showed that $A_1^n$ turns positive at $x\sim 0.5$, while up to the highest measured $x$ value of 0.61 $\Delta d/d$ remains negative, in contrast to the pQCD prediction. Subsequent theoretical studies following the 6 GeV results claimed that quark orbital angular momentum could delay the upward turn of $\Delta d/d$ to higher $x_{Bj}$ or non-perturbative nature of the strong interaction could keep it negative all the way to $x_{Bj}=1$ as predicted in Schwinger-Dyson approach with di-quark model assumption. With the 12 GeV upgrade of JLab, a new experiment on $A_1^n$ (E12-06-110)$^1$ was carried out using a 10.4 GeV beam, a polarized $^3$He target, and the HMS and the Super-HMS (spectrometers) in Hall C. This measurement reached a deeper valence quark region: $x\sim 0.75$. When combined with the expected data from the upgraded CLAS12 experiment on the proton $A_1^p$, we will be able to reveal whether $\Delta d/d$ turns positive (as in pQCD) or remain negative at high $x$ (as in RCQM or Schwinger-Dyson/di-quark). We will present the physics of $A_1^n$ and report the analysis status for the $A_1^n$ experiment. Performance of the upgraded polarized $^3$He target will also be presented.
$^1$ This work is supported in part by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-FG02-94ER4084.
The spin structure of the proton and the spin-momentum correlations between the proton and its constituent partons are currently the main focus of the PHENIX cold QCD program at the Relativistic Heavy Ion Collider. The large amounts of data collected using the PHENIX detectors in collisions utilizing longitudinally or transversely polarized protons only available at RHIC continue to further our understanding of the subjects. The longitudinal double spin asymmetries ($A_{LL}$) of various final state particle production in polarized $\vec{p}+\vec{p}$ collisions at RHIC energies give direct access to the gluon polarization inside the proton. On the other hand, the transverse single spin asymmetries ($A_N$) of a variety of particle production in collisions between a polarized proton and a proton or ion ($p^{\uparrow}+p/A$) in different pseudorapidity regions provide variable sensitivities to different mechanisms that give rise to the $A_N$. This talk will highlight the recent $A_{LL}$ and $A_N$ measurements from direct photons, neutral and charged hadrons, jets, and open heavy flavor in 200 and 510 GeV collisions.
Diquark bonds formed from valence quarks across a nucleon-nucleon pair have been proposed as the fundamental quantum chromodynamics (QCD) physics causing short-range correlations (SRC) in nuclei. The 12-quark "hexadiquark" QCD state - effectively two SRC bound together - is also proposed as the cause of distortions of quark distribution functions in nuclei. While SRC have been extensively studied both experimentally and theoretically, notably by the CLAS collaboration in conjunction with the EMC effect, their underlying cause at the QCD level has remained a mystery. The diquark formation model, if shown to be the source of SRC in nuclei, represents a breakdown of the assumption of scale separation in effective field theories and forms a bridge between QCD and nuclear physics. Implications of the hexadiquark state contained within the $^4$He nuclear wavefunction on the ATOMKI X17 signal will also be discussed.
Tests of Symmetries and the Electroweak Interaction
The decay of the free neutron into a proton, electron, and antineutrino is the simplest beta decay system. The beta electron-antineutrino angular correlation (a-coefficient) is one of several important experimental parameters of neutron decay. Together these can be used to measure the weak decay couplings G_A and G_V, determine important fundamental parameters of the weak nuclear force, and conduct precision low energy tests of physics beyond the Standard Model. The aCORN experiment uses a novel “wishbone asymmetry” method that does not require detailed proton spectroscopy. aCORN ran at the NIST Center for Neutron Research in 2013-2014 and then at the new high flux end position NG-C in 2015-2016. The combined result, published in 2021, has an overall uncertainty of 1.7%. Details of the experiment and analysis, with a discussion of future prospects, will be presented.
The Nab collaboration aims to make the world’s most precise, by about a factor of 6, measurement of the electron-neutrino angular correlation parameter “a” and the Fierz interference term “b” in cold neutron beta decay. Along with the neutron lifetime, these measurements provide a complementary test of various extensions to the standard model. Nab is 4 m tall asymmetric time of flight spectrometer with custom 100 mm^2, 127 pixel Si detectors on either end. Nab is currently in its commissioning phase at the Spallation Neutron Source at Oak Ridge National Lab in the USA and will collect physics data from 2022-2025. The Canadian Nab group is responsible for testing the novel large area Si detectors used in the experiment where we have built a steerable 30 keV proton accelerator at the University of Manitoba (UofM) for this purpose. This talk will motivate and provide an overall status of the Nab experiment and present the 30 keV proton source at UofM with recent detector testing results.
The instrument PERKEO III was used to measure most precisely the beta asymmetry in neutron decay at the cold neutron beam line PF1b of the ILL, Grenoble. From this measurement, we extract the ratio of nucleon axial-vector and vector couplings. When combined with the neutron lifetime, this provides the CKM matrix element $V_{ud}$ with only a factor two in precision to the combined result from superallowed nuclear decays. PERKEO's successor, the PERC instrument, is currently being commissioned at the FRM II, Garching, which aims at an improved measurement of the beta asymmetry by a factor of five. Pulsed neutron beams are key to eliminate or control systematics in both experiments. The inherent pulse structure at the proposed ANNI beamline at the ESS, Lund, will increase statistics by more than an order of magnitude for these measurements.
In this talk, I will discuss recent results by the PERKEO III collaboration and present the status of its successor PERC.
We report on a precise measurement of the antineutrino-electron angular
correlation (the $a$ coefficient) in free neutron beta-decay obtained with the
$a$SPECT experiment. The $a$ coefficient is inferred from the recoil
energy spectrum of the protons. Protons are detected in $4\pi$ in the
$a$SPECT spectrometer using magnetic adiabatic collimation with
an electrostatic filter. We have obtained $a = -0.10430(84)$ (as
published in Phys. Rev. C 101, 055506 (2020)) which is the most precise measurement of the neutron $a$ coefficient to date. We also give a preview on further
analysis efforts and our derivation of the Fierz term.
Baryon number violation is a key ingredient of baryogenesis. Since the famous parity violation paper of Lee and Yang, it has been known that there could also be a parity conjugated copy of the standard model particles. The existence of such a mirror universe has specific testable implications, especially in the domain of neutral particle oscillation, viz. the baryon number violating neutron to mirror-neutron oscillation. It was shown that such $n-n'$ oscillations could happen rapidly with an oscillation time as small as a second. Consequently, there were many experiments which searched for $n-n'$ oscillation, and reported having found no evidence of $n-n'$ oscillation [1,2,3]. Early efforts assumed a zero mirror magnetic field, and the $n-n'$ oscillation time is best constrained to $\tau^{B'=0}_{nn'}<448~$s (90\% C.L.). But, later efforts have scanned for non-zero mirror magnetic field as well [4,5]. Such mirror magnetic fields could be bound to the reference frame of the Earth. Even though the experiments report having found no evidence of $n-n'$ oscillation, reanalysis of some of these results have identified three particular anomalies which could point to the detection of $n-n'$ oscillation [5,6]. All but one of these efforts were conducted at the Institute Laue-Langevin in Grenoble, France, with the most recent search having been conducted at the Paul Scherrer Institute in Villigen, Switzerland [7,8]. The search for $n-n'$ oscillation having now been conducted at two locations, along with their null results, allows us to constrain, not only the magnitude of a possible mirror magnetic field, but also its direction. The search for $n-n'$ oscillation conducted at PSI using the nEDM apparatus will be described. Then, the results of the study to constrain the direction of possible mirror magnetic field, which are consistent with the null-results as well as the three anomalies, will also be presented.
The theory of “mirror matter” restores parity to the Standard Model of Particle Physics by hypothesizing a copy of the Standard Model particles and interactions with right-handed weak interactions. Since mirror matter would only rarely interact with normal matter, particles predicted by this theory could be one possible candidate for dark matter. A version of this theory with non-degenerate particle masses suggests that the $>4 \sigma$ discrepancy between the neutron lifetime $\tau_n$ measured in two ways, either counting by neutrons remaining in a trap or by counting decay products produced from a cold neutron beam, could be indicative of neutrons oscillating into their mirror neutron partners. In the event of a small mass difference $\Delta m$ between the normal and mirror neutron states, the strong magnetic field present in the most precise Beam Lifetime experiment could enhance the probability of oscillations and cause an apparent increase in the measured $\tau_n$. An experiment at the Spallation Neutron Source at Oak Ridge National Lab probed this theory by searching for the hypothesized disappearance and reappearance of neutrons passing through a B$_4$C absorber inside a magnetic field. Here we present new limits on neutron oscillations into non-degenerate mirror matter. We will also discuss further efforts to improve these limits and new searches for other models of $n$ oscillations at neutron scattering sources.
Physics at High Energies
The ATLAS experiment has performed measurements of $B$-meson rare decays proceeding via suppressed electroweak flavour changing neutral currents, and of mixing and CP violation in the neutral $B^0_s$ meson system. This talk will focus on the latest results from the ATLAS collaboration, such as rare processes $B^0_s \to \mu \mu$ and $B^0_d \to \mu \mu$, and CP violation in $B^0_s \to J/\psi\ \phi$ decays. In the latter, the Standard Model predicts the CP violating mixing phase, $\phi_s$, to be very small and its SM value is very well constrained, while in many new physics models large $\phi_s$ values are expected. The latest measurements of $\phi_s$ and several other parameters describing the $B^0_s \to J/\psi\ \phi$ decays will be reported.
Measurements of multiboson production at the LHC are important probes of the electroweak gauge structure of the Standard Model and for contributions from anomalous couplings. In this talk we present recent ATLAS results on Zy production in association with jet activity. These differential measurements provide inputs and constraints on modeling of the Standard Model. In addition we will present a first measurement of di-boson polarization at the LHC. Moreover, precise boson, diboson and Higgs differential cross-section measurements are interpreted in a combined Effective Field Theory analysis, allowing to systematically probe gauge boson self-interactions.
Very detailed measurements of Higgs boson properties and its interactions can be performed with the full Run 2 pp collision dataset collected at 13 TeV, shining light over the electroweak symmetry breaking mechanism. This talk presents the latest measurements of the Higgs boson coupling properties by the ATLAS experiment in various decay bosonic and fermionic channels, as well as their combination. Results on production mode cross sections, Simplified Template Cross Sections, and their interpretations are presented. Specific scenarios of physics beyond the Standard Model are tested, as well as a generic extension in the framework of the Standard Model Effective Field Theory, and in the framework of an Effective Field Theory.
Precision Physics at High Intensities
Despite the success of the Standard Model (SM) of particle physics, there exist phenomena that it cannot explain, suggesting the existence of a more complete theory which is yet unknown. Rare decays of hadrons containing a b-quark provide a powerful way of exploring theories of physics beyond the SM. Hypothetical new particles could enhance the decay rates of these rare processes to a level detectable by existing experiments. An overview of the recent results obtained by the LHCb collaboration in the search for rare b-hadron decays is presented, including prospects in view of the LHCb upgrade.
Charged lepton flavor violation has long been recognized as unambiguous signature
of New Physics. Here we describe the physics capabilities and discovery potential
of New Physics models with charged lepton flavor violation in the tau sector as its
experimental signature. Current experimental status from the B-Factory experiments
BaBar, Belle and Belle II, and future prospects at Super Tau Charm Factory, LHC,
EIC and FCC-ee experiments to discover New Physics via charged lepton flavor
violation in the τ sector are discussed in detai
Quark Matter and High Energy Heavy Ion Collisions
The Solenoidal Tracker at RHIC (STAR) experiment is dedicated to the study of the different phases and properties of high energy-density QCD matter produced in ion-ion collisions at RHIC. A major current focus is centered on mapping the QCD phase diagram, elucidating the transport and anomalous transport properties of the Quark-Gluon Plasma (QGP), and testing for chiral symmetry restoration. In this STAR overview talk, I am planning to present our recent measurements that are expected to shed light on the initial stages of heavy-ion collisions, the temperature-dependent viscosity (\eta/s(T)), and the chiral properties of the QGP.
The PHENIX result at the Relativistic Heavy Ion Collider has collected data scanning system sizes from pp and $^3$HeAl to Au+Au and U+U at collision energies from $\sqrt{s_{NN}}=7.7-510$ GeV. The extensive measurements from these data improve our understanding of the Quark Gluon Plasma and the origin of the proton spin. PHENIX's measurements of $\pi^0$ mesons, photons, heavy flavor particles, and jets probe the formation of the QGP, and measurements of azimuthal anisotropies are sensitive to collective effects and the initial geometry of the collision. A selection of results from PHENIX with an emphasis on results from heavy ion collisions will be shown.
The 2015 Nuclear Science long range plan recommendation describes the importance for RHIC to complete its scientific mission and the crucial role sPHENIX plays in achieving that goal. sPHENIX is specifically designed to make state-of-the-art jet, upsilon and heavy flavor measurements to probe the inner workings of the Quark Gluon Plasma (QGP) produced in heavy ion collisions at RHIC. The unique capabilities of sPHENIX including its large data collection rate provide opportunities to also study bulk phenomena of the QGP as well as explore cold QCD. sPHENIX includes calorimetery and tracking detectors at mid-rapidity ($|\eta|<1$). The calorimeter system is composed of electomagnetic (EMCal) and hadronic calorimeters to precisely measure the energy of the jets. The EMCal also allows for measurements of electrons from quarkonia as well as photons. The precision tracking system will enable jet substructure measurements and tagging of heavy flavor quarks. sPHENIX, which is currently under construction, is scheduled to begin taking Au+Au data in February 2023. The current status, proposed run plans and anticipated precision for key observables will be presented.
Over the last 5 years, the Jet Energy loss Tomography with a Statistically and Computationally Advanced Program Envelope (JETSCAPE) collaboration has constructed and publicly released an extensive framework to design, build and test event generators for high energy heavy-ion collisions. The physics of these collisions involves many aspects, such as the initial state of incoming nuclei, the thermalization of the deposited energy, the viscous fluid expansion, hadronic cascade, and the propagation of hard jets and/or rare particles through the evolving medium. The study of such an elaborate system requires a modular and extensible simulator. The current publicly available code base contains a framework that allows users to use existing physics modules, or extend functionality by adding new modules, and Bayesian routines to test the veracity of model choices. State-of-the-art default modules can be used to carry out simulations of the formation of the quark-gluon plasma (QGP) in nuclear collisions and study jet quenching in these plasmas. Parameters introduced in this factorized multi-stage approach are constrained by Bayesian methods in comparison with a subset of experimental data. Posterior distributions can then be used to make rigorous comparisons between theory and experiment. I will outline recent results from this exciting new approach in high energy nuclear physics, and sketch the evolving picture of bulk and hard dynamics in heavy-ion collisions.
Particle and Nuclear Astrophysics
The rapid neutron capture process, or r process, is expected to produce some of the heaviest elements observed to exist in nature. In the immediate aftermath of the r process in astrophysical environments, the nuclei produced are extremely neutron-rich and, therefore, undergo a long period of radioactive decay proceeding through a broad swath of the chart of nuclides, the effect of which can drive a range of observables associated with these events. In this work, we discuss Jade, a radioactive decay network which can include both ground and isomeric nuclear states in modeling the radioactive decay of r process ejecta.
Core-collapse supernovae are one of the most complex phenomena in the universe. Not only are they one of the sites of the production of the heavy elements which enable the existence of life, but their cores are also one of the densest environments we can indirectly probe. At such densities, the matter may no longer consist only of hadronic degrees of freedom but undergo a phase transition to quark matter. In this talk, I will discuss the implications of such a transition on the neutrino emission from core-collapse supernovae.
QCD, Hadron Spectroscopy, and Exotics
LHCb is at the forefront of searches for new exotic hadrons through spectroscopy in high energy physics and the recent results published from proton-proton collision data taken by the experiment will be presented. In particular, the observation of a $J/\psi\Lambda$ resonance in $B^{-}\to J/\psi\Lambda\bar{p}$ decays consistent with a strange pentaquark, and two new tetraquarks (one doubly charged and one neutral) found in $B^{0}\to \bar{D^{0}}D_{s}^{+}\pi^{-}$ and $B^{+}\to D^{-}D_{s}^{+}\pi^{+}$ decays will be discussed, along with other results.
Many exotic resonances have been recently observed at LHC. In this report a search for low-mass structures in the JPsi/JPsi mass spectrum in pp collisions at sqrt(s)=13TeV is presented. The new results are based on data collected by the CMS experiment during the full Run II.
A production and decay model that incorporates theoretical and previously unrecognized experimental constraints on the LHCb pentaquark states is presented. The model satisfies all constraints and successfully fits the entire invariant mass distribution (unlike previous work). We find strong evidence for Sigma_c D molecular states along with threshold cusp and triangle singularities. Suggestions for future experiments will be made.
The strong interaction between quarks and gluons, from which hadrons are built, is theoretically described by quantum chromodynamics. However, the role of gluons and how they affect the properties of hadrons is still unresolved. The discovery of several unexpected and possibly exotic hadrons in recent years highlights the need for precise spectroscopic measurements to understand the nature of the strong interaction. The status of the search for exotic contributions in photoproduction data from the GlueX experiment at Jefferson Lab in $\eta^{(')}\pi$ systems will be presented. Specifically, results on the production of the $a_2(1320)$ meson in these key channels, which are first steps in the search for exotic quantum-number hybrid mesons, will be discussed. The application of a partial wave analysis exploiting the polarization of the photon beam available to the GlueX experiment, and implications for the measures needed to identify the hybrid will be discussed.
Dark Matter
Cold dark matter is one of the major constituents of the leading cosmological model for our Universe, with many ongoing experimental efforts at directly detecting interactions of the hypothetical particle with terrestrial detectors.
SuperCDMS SNOLAB is a Generation-2 dark matter experiment under construction at SNOLAB in Sudbury, Canada. The experiment will employ two types of state of the art cryogenic Ge and Si detectors, 24 in total, capable of detecting sub-keV energy depositions from potential dark matter interactions. This talk will discuss the ongoing constructions of SuperCDMS SNOLAB experiment as well as future operational plans, with the goal of improving sensitivity to dark matter particles over a broad range of eV to GeV, by orders of magnitude as compared to existing limits.
The SPICE and HeRALD experiments aim to probe dark matter (DM) masses down to 10 MeV, with upgrade paths to sub-MeV masses. The project is currently in a preparatory R&D phase focused on first pushing Transition Edge Sensor (TES) recoil energy thresholds into the sub-eV regime, and then applying this next generation of sensors to a variety of well-motivated target materials. The HeRALD portion of the effort employs a superfluid 4He target. Helium's nuclear recoil sensitivity benefits from both a low-mass target nucleus and a unique quantum evaporation phonon readout method. The complementary SPICE effort employs polar crystal target materials, motivated by their strong couplings to dark photon mediated DM.
Axions represent a leading class of dark matter candidate that has gained considerable interest in recent years. In order to probe its largely unexplored axion parameter space across multiple frequency decades, new experimental techniques are required. The HAYSTAC (Haloscope At Yale Sensitive To Axion Cold dark matter) experiment is a tunable microwave cavity experiment searching for axions, which also serves as an R&D testbed for new technologies in the 10-50 𝜇eV mass range. HAYSTAC Phase 2 has already successfully operated and published data with a receiver based on squeezed-vacuum states to evade the Standard Quantum Limit. This was the first-ever dark matter experiment to do so, and along with LIGO, only one of two search experiments in fundamental physics to utilize squeezed states for data production. In this talk, I will review recent science results from HAYSTAC, as well as new resonator and receiver technologies under development. These include photonic band gap resonators, and a cavity entanglement and state-exchange scheme which promises to accelerate the search by an order of magnitude.
The DMRadio suite of experiments seeks to search for one of the most promising Dark Matter (DM) candidates, the axion, via an optimized resonant lumped element search. In order to cover as wide of a parameter space as possible, each of the DMRadio experiments is designed to cover specific complementary mass regions starting from 5 kHz (≈ 20 peV) in the DMRadio-50L experimental all the way up to 200 MHz (≈ 1 𝜇eV) with the DMRadio-m3 experiment. At the same time, the DMRadio-50L experiment will serve as a testbed for accelerated axion searches with quantum sensors. In this talk, we will present an overview of the DMRadio program, discuss the optimization campaign together with the current construction efforts on the DMRadio-50L experiment, discuss the future goals for the DMRadio-m3 experiment, as well as the development of a future search for GUT-scale QCD axions in the MHz region.
Precision Physics at High Intensities
PREX-II and CREX were two experiments designed to measure the neutron skin thickness in $^{208}$Pb and $^{48}$Ca respectively. Both experiments used the parity-violating electron scattering (PVES) technique, which involved measuring the parity-violating cross-section asymmetry ($A_{pv}$) between left- and right-handed longitudinally polarized electron scattering off an unpolarized target. The neutron radius of each nucleus is then extracted from the weak form factor which is itself extracted from $A_{pv}$. Obtaining an accurate measurement of $A_{pv}$ is technically challenging because of the small size of $A_{pv}$, (on the order of 1 ppm for both $^{208}$Pb and $^{48}$Ca) as well as sources of noise and false asymmetries that may arise from beam instabilities and the polarimetry measurement. Additionally, both experiments had to be designed to accomodate high-Z targets, which means constructing detectors capable of high-rate measurement, as well as engineered radiation controls to protect experimental equipment. A number of experimental systems were constructed and deployed to minimize the contributions from source of false asymmetry, and make the measurement of $A_{pv}$ technically feasible. PREX-II's measured $A_{pv}$ for $^{208}$Pb is 550 ± 16 (stat) ± 8 (syst) ppb and CREX's measured $A_{pv}$ for $^{48}$Ca is 2668 ± 106 (stat) ± 40 (syst) ppb. This corresponds to a neutron skin thickness for $^{208}$Pb of 0.278 ± 0.078 (exp) ± 0.012 (theo) fm and a skin thickness for $^{48}$Ca of 0.121 ± 0.026 (exp) ± 0.024 (theo).
The technique of parity-violating electron scattering, involving measurements of the asymmetry in the scattering of longitudinally polarized electrons off fixed targets, has become increasingly precise over the past three decades. Such asymmetries are sensitive to weak neutral current interactions (mediated by the Z boson) between electrons and quarks, or between two electrons, and can be used to probe for the limits of validity of the electroweak theory in a manner complementary to direct searches for new physics at high energy scales at colliders. Experiments planned for the next decade in elastic electron-electron scattering (MOLLER at Jefferson Lab), elastic electron-proton scattering (P2 at the Mainz MESA facility), and parity-violating deep inelastic scattering (SOLID at Jefferson Lab), will significantly improve determinations of the electron’s weak charge, proton’s weak charge, and the axial-vector electron-quark coupling constants, respectively. All of these measured quantities can be used to extract values of the weak mixing angle at low energies that can be used to test the Standard Model and probe for new physics beyond the Standard Model at MeV and multi-TeV scales, complementary to direct searches at high energy colliders.
The hadronic weak interaction provides unique probe of the strong dynamics that confine quarks into nucleons in the low energy non-perturbative QCD regime. Precision measurements of parity violating observables in few body NN systems can provide important benchmarks for models that aim to describe this low-energy non-perturbative QCD regime, as well as effective models that seek to describe the NN weak interaction itself. Recent theoretical work [1,2] implies a large parity-odd neutron spin rotation (NSR) in $^{4}$He just outside the previous measurement of $d\phi/dz = [+2.1 \pm 8.3(stat.) \pm 2.9(sys.)] \times 10^{-7}$ rad/m [3]. Upgrades to the NSR apparatus enable an experimental sensitivity of less than $[\pm 1.0(stat.) \pm 1.0(sys.)] \times 10^{-7}$ rad/m [4] on the NG-C beamline at NIST. The status of the NSR apparatus as well as implications of the recent measurements of the weak pion exchange component of the NN weak interaction [5] and in the n-$^{3}$He system [6] will be discussed.
[1] S. Gardner, W. C. Haxton, and B. R. Holstein, Ann. Rev. Nucl. Part. Sci. ${\bf 67}$, 69 (2017).
[2] R. Lazauskas and Y.-H Song, Phys. Rev. C ${\bf 99}$, 054002 (2019).
[3] H. E. Swanson ${\it et \hspace{1mm} al.}$, Phys. Rev. C ${\bf 100}$, 015204 (2019).
[4] W. M. Snow ${\it et \hspace{1mm} al.}$, Rev. Sci. Inst. ${\bf 94}$, 055101, (2015).
[5] D. Blyth ${\it et \hspace{1mm} al.}$ (NPDGamma Collaboration), Phys. Rev. Lett. ${\bf 121}$, 242002 (2018).
[6] M. T. Gericke ${\it et \hspace{1mm} al.}$ (n$^3$He Collaboration), Phys. Rev. Lett. ${\bf 125}$, 131803 (2020).
A nuclear anapole moment (NAM)--a magnetic moment associated with a localized toroidal current--arises due to hadronic parity violating interactions between nucleons. The NAM can be detected via the coupling of its local magnetic field to the spin of a penetrating electron, such as an unpaired valence electron in a neutral atom. ZOMBIES is an experiment to measure NAMs using neutral polar molecules, where the NAM serves to mix hyperfine/rotational states of opposite parity. A magnetic field is used to apply Zeeman shifts that bring these states to near degeneracy, leading to parity-violating asymmetries of order unity. This talk will describe a proof-of-principle measurement with ZOMBIES, and prospects for near- and long-term measurements of many NAMs using this approach.
Quark Matter and High Energy Heavy Ion Collisions
I will review recent lattice QCD results on heavy flavor probes of QGP, including in-medium bottomonium masses and widths, the complex heavy quark potential at non-zero temperature, and the heavy quark diffusion coefficient.
In ultra-relativistic heavy-ion collisions a hot and dense QCD matter, called Quark- Gluon Plasma (QGP), is produced. Heavy quarks (charm and beauty) are powerful probes to investigate the production and properties of the QGP. They are produced in hard scattering processes with large momentum transfer before the formation of the QGP, thus experiencing the full evolution of the system. The partons transversing the QGP undergo energy loss by collisional and radiative processes. The dependence of these processes on the mass and color charge of partons can be studied with charm and beauty quarks. In this talk, I will present a review of the most recent open heavy-flavor hadron measurements at RHIC and at the LHC. I will discuss what we have learnt from these results, and project future prospects.
The recent observations of enhanced particle yields, including 𝐽/𝜓, in high event multiplicity 𝑝+𝑝 collisions at RHIC and LHC suggest possible strong contributions from semi-hard Multi-Parton Interactions (MPI) as well as other final state interactions. These new results challenge not only the traditional “single hard-scattering” pQCD description that is widely used in calculating particle yields in p+p collisions, but also the interpretation of other important observables, such as event centrality in the extreme limit in a small system heavy ion collisions and certain event multiplicity dependent transverse spin asymmetries in polarized 𝑝+𝑝(𝐴) interactions. To gain further insight into particle production mechanisms in hadronic interactions, we have studied the 𝐽/𝜓 yield in the forward (and backward) rapidity in p+p and p+Au collisions as a function of event multiplicity and observed a strong dependence of the 𝐽/𝜓 relative yields vs event multiplicities determined over a broad range of rapidity. The latest findings shade new lights on our understanding of the possible correlations of particle production and event global and/or local activities in hadron-hadron collisions. The latest status of this study using the PHENIX 2015 data will be presented.
Quarkonia are considered as excellent probes to understand the properties of the quark gluon plasma (QGP), which is expected to be created in heavy ion collisions. In particular, experimental results of azimuthal anisotropy for charmonium states are expected to provide crucial information on the dynamics of quarkonia as well as the QGP properties. In this presentation, we present a detailed study of the elliptic and triangular flow for charmonium states with the CMS experiment. The second-order ($v_{2}$) and third-order ($v_{3}$) Fourier coefficients for prompt and nonprompt J/$\psi$ are reported with high precision in PbPb collisions. In addition, we report the $v_{2}$ and $v_{3}$ values of prompt $\psi(2S)$ mesons for the first time in heavy ion collisions. The results are compared with related measurements of charmonium modification and discussed in terms of various quarkonium in-medium effects.
The analysis of J/$\psi$ photoproduction in ultra-peripheral collisions
(UPC) of heavy ions allows for perturbative QCD considerations which
address the gluon saturation and nuclear shadowing. J/$\psi$ and $\psi^{'}$
photoproduction cross sections in Pb--Pb UPC, measured by ALICE both at forward
and central rapidities, are compared with available QCD-based models.
The first measurement of the cross section for coherent J/$\psi$ production
in Pb--Pb UPC as a function of |t| provides a tool to constrain
the transverse gluonic structure in nuclei at very low Bjorken-$x$.
Preliminary results on J/$\psi$ photoproduction and exclusive dimuon
production in p--Pb UPC are presented.
The light-meson photonuclear production in UPC at the LHC
approaches the black-disk limit of QCD. The cross sections of the
$\rho^{0}$ coherent photoproduction in Pb--Pb and Xe--Xe UPC were
measured for different nuclear-breakup classes. The results are
compared with model predictions.
Nuclear Forces and Structure, NN Correlations, and Medium Effects
One of the motivations for the recent upgrade of Jefferson Lab was to precisely explore the connection between the fundamental quarks and gluons of Quantum Chromodynamics (QCD)- the accepted theory of the strong force - and the effective hadron descriptions of the strong interaction. The ultimate goal being an accurate understanding of the emergence of nuclei from QCD. The key experiments of this program typically aim to study fundamental QCD prediction in nuclei, in search of the onset of these phenomena. Many of the early experiments that have been completed at the upgraded JLab are part of this program designed to address the connection between quarks and nuclei.
We will discuss some puzzling new results from the search for squeezed protons and the onset color transparency, a rigorous prediction of QCD. We will also highlight some upcoming experiments.
In contrast with inclusive measurements on nuclei, detecting hadrons originating from nuclear breakup provide additional control over the nuclear configurations playing a role in the scattering process. On the flip side, however, final-state interactions (FSI) of these breakup products need to be accounted for in the physical interpretation of the measurement. These FSI can obscure the physics signal one is after, but they can also be leveraged to learn about the space-time evolution of hadronization.
I will discuss dominant FSI mechanisms in nuclear breakup reactions in different kinematics, covering JLab and the future electron-ion collider (EIC). I will then show how they have been accounted for in physics models and MC tools, including comparisons to data and potential applications at EIC.
Recently developed effective theories of QCD in matter have enabled the derivation of medium-induced branching processes as a function of nuclear opacity. I will demonstrate how splitting functions can be derived for both light partons and heavy quarks and discuss how parton showers in matter differ from the ones in the vacuum. These advances allow us to bridge the gap between high energy and nuclear theory and introduce higher order and resumed calculations to QCD phenomenology with nuclei. I will demonstrate this with three examples: i) inclusive light and heavy flavor meson production that can shed light on the physics of hadronization; ii) light and heavy jet production to constrain the transport properties of cold nuclear matter, and iii) jet substructure that, in the long run, can provide the most detailed insights into the microscopic physics of multiple parton interactions in nuclei.
All information about the initial state of partons in a nucleon/nucleus before a hard scattering takes place is encoded in universal, non-perturbative functions collectively known as “parton distribution functions” (PDFs). Depending on the physical processes and kinematic region studied, different PDFs can be extracted, e.g., unpolarised/polarised PDFs, generalised PDFs, etc. In the perturbative approach, their determination is based on global fits to available data, measured in appropriate processes. The most widely studied and best known PDFs are those of a free proton in the collinear regime, and the cleanest experiment for their extraction is the Deep Inelastic Scattering (DIS) of lepton and proton. When the proton is replaced by a nucleus, the observed cross-sections differ non trivially; under the assumption that the perturbative framework is applicable, the nuclear forces holding together the nucleus seem to affect the distribution of momentum of the partons inside each bound nucleon. Therefore, a set of medium-modified or nuclear PDFs (nPDFs) are required to describe processes involving nuclei. Unlike the free proton PDF case for which DIS data from the HERA collider are available, in the nuclear case only fixed target experiments have been conducted to date. These have a limited kinematic coverage and as a consequence the nPDFs are far less constrained than those in free protons. This picture will changed drastically with the EIC, that will measure DIS off a variety of nuclei in collider mode, putting for the first time proton and nuclear experiments at the same level. In this talk I will discuss the possibilities of improving nPDFs at the EIC using DIS and other observables.
Particle and Nuclear Astrophysics
We present high statistics measurements of 15 cosmic ray nuclei, H to Si and Fe, based on 10 years of the AMS data.
The $\beta$-decay study of indium-133 provides a unique connection between nuclear structure and astrophysics. On one hand, $^{133}$In is a perfect $\beta$-decay demonstrator of r-process nuclei in the vicinity of $N=82$ owing to its extreme neutron-proton asymmetry and thus large $Q_{\beta}$ and $Q_{\beta n}$ windows. On the other hand, its decay daughter, $^{133}$Sn, is simple in its nuclear structure due to the proximity to the doubly magic $^{132}$Sn. Thus, a measurement on the $\beta$-strength function of $^{133}$In allows us to unravel how the r-process nuclei decay, benchmarking the state-of-the-art nuclear models with a simple representation. This is extremely crucial for the nuclear models in assessing their prediction power in more exotic regions that are out of experimental reach.
We did the experiment at the ISOLDE decay station (IDS). The neutron time-of-flight array, INDIe [1-3], was installed at IDS to measure neutron spectroscopy from $^{133}$Sn following the $^{133}$In $\beta$ decay. Several strong and isolated neutron resonances were observed below Ex=6 MeV, including the previously observed state at Ex=3.56 MeV [4-6]. More importantly, we quantified for the first time the single GT strength of the $\nu g7/2\rightarrow\pi g9/2$ transformation which dominates the $\beta$ decay of a large number of exotic nuclei to the southeast of $^{132}$Sn. In this contribution, we will present our latest results regarding the excitation energies, branching ratios, and log$ft$ of a series of neutron unbound states newly observed in the $^{133}$In decay. Our experimental findings were compared to the large-scale shell-model calculations employing several different effective interactions. The result suggests the proton excitation across $Z=50$ plays an important role to understand quantitatively the GT strength measured in this work.
[1] W.A. Peters et al., Nucl. Inst. Meth. A 836, 122 (2016).
[2] S.V. Paulauskas et al., Nucl. Inst. Meth. A 737, 22 (2014).
[3] R. Lica et al., in preparation.
[4] P. Hoff et al., Phys. Rev. Lett. 77, 1020 (1996).
[5] V. Vaquero et al., Phys. Rev. Lett. 118, 202502 (2017).
[6] M. Piersa et al., Phys. Rev. C 99, 024304 (2019).
During classical nova nucleosynthesis, the 30P(p,gamma)31S reaction rate critically affects the mass flow into the A=30-40 range, impacting the abundances of isotopes of phosphorus, sulfur, and silicon. Direct measurement of the (p,γ) reaction is not currently possible due to insufficient beam intensities. The rate of this reaction depends on undetermined spectroscopic strengths of low-lying resonances in 31S, located between 6 and 7 MeV in excitation energy. Due to experimental challenges to measure the proton spectroscopic factors on unstable nuclei, we performed a 30P(d,pγ)31P neutron transfer reaction measurement using the newly commissioned GODDESS (GRETINA-ORRUBA: Dual Detectors for Experimental Structure Studies) detection system—with an 8 MeV/u 30P beam, from RAISOR at ATLAS, in order to provide constraints on the spectroscopic strengths for 31S levels via mirror symmetry. Details of the experiment and data analysis, including excitation energy spectra, proton-γ matrices, angular distributions, and spectroscopic factors, will be presented.
QCD, Hadron Spectroscopy, and Exotics
Parton dynamics inside the proton and hadronization are key areas of research in Quantum ChromoDynamics (QCD) at LHCb at the Large Hadron Collider. A large hard scale above the electroweak scale reached by hadron collisions at unprecedentedly high energies enables measurements sensitive to multiple scales that potentially explain interesting nonperturbative dynamics inside the proton and in hadronization. Measurements of final state particles in association with weak boson production are theoretically favorable due to being well into the factorization regime in perturbative QCD where precise predictions can be made with reduced uncertainties. As a forward spectrometer, the LHCb detectors can access complementary kinematic regions in partonic variables to other general purpose detectors at LHC and retain a large fraction of heavy flavor production. These advantages together with excellent particle identification and full jet reconstruction capabilities, and a low number of multiple collisions at LHCb opened up opportunities for a variety of unique and clean QCD measurements. This talk will highlight selected recent results probing transverse-momentum-dependent (TMD) distributions of quarks, its spin-momentum correlations, and intrinsic charm inside the proton and TMD fragmentation functions in jets.
The transverse-momentum-dependent parton distributions (TMDs) provide a 3D imaging of the proton and other hadrons in high-energy scattering experiments, such as those at Fermilab, Jefferson Lab, RHIC and LHC. Recent years have seen significant progress in the global fitting of TMDs from experiments, and along with that is a lattice QCD program aiming at first-principles calculation of these quantities in the non-perturbative domain. Thanks to the breakthroughs in theory, especially the large-momentum effective theory (LaMET), it is now feasible to calculate both quark and gluon TMDs from a set of lattice TMDs through perturbative matching. In this talk, I will introduce the LaMET approach to solve for TMDs, and review the encouraging lattice results on TMDs and their non-perturbative evolution.
A detailed understanding of the proton's properties is incomplete without the knowledge of the transverse spin structure of its constituent quarks, which may be accessed in proton-proton collisions via hadron-in-jet and di-hadron asymmetries. Both observables couple the quark transversity distribution to a spin dependent fragmentation function. For the di-hadron channel it is the collinear interference fragmentation functions, while for the hadron-in-jet channel it is the transverse-momentum-dependent (TMD) Collins function. The fact that these complementary channels probe the same physics, albeit within different theoretical frameworks, provides a unique opportunity to study TMD evolution and test factorization breaking in the TMD formalism. In this talk we present recent results from STAR's midrapidity ($\left|\eta\right|<1$) transverse spin program along with comparisons to model calculations using $\sqrt{s} = 500$ GeV $ p^\uparrow p$ collisions from 2011 and $\sqrt{s} = 200$ GeV $ p^\uparrow p$ collisions from 2012 and 2015. The Collins asymmetries from 2012 and 2015 and di-hadron correlations from 2015 represent the most precise $\sqrt{s} = 200$ GeV results released to date. The di-hadron correlations and Collins asymmetries from 2011 constitute the first statistically significant signals reported at $\sqrt{s} = 500$ GeV.
Nuclear parton distribution functions (nPDF) play a crucial role in the interpretation of scattering data taken in proton-nucleus and nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC), the Large Hadron Collider (LHC) and in the near future at the Electron-Ion Collider (EIC). However, analyses of these nPDFs are still far away from the precision obtained in free proton PDF fits. To close this gap, multiple groups, including EPPS, nCTEQ, nNNPDF and TUJU, have been steadily updating their analyses with precise new LHC data and with methodological improvements. We review the general framework of nuclear PDF determinations, present an overview of the most recent developments in the field and compare the results obtained by the various groups.
Gluon nuclear Parton distribution functions (nPDFs) have been the subject of many studies over the past years, since they are important for many processes and difficult to constrain. Recently, nCTEQ15 nPDFs have been updated with vector boson production data to address this issue. To constrain the gluon nPDF further, particularly at low x, we present two new global analyses adding single inclusive light and heavy meson production data. The former analysis adds pion and kaon production data and investigates the impact of the fragmentation function choice.
The second analysis extends this further by including both open heavy flavored mesons and heavy quarkonia using a data driven approach. The result is a consistent new nPDF fit with greatly reduced gluon uncertainties.
The ${\rm M{\scriptsize AJORANA}}$ ${\rm D{\scriptsize EMONSTRATOR}}$ is an experiment designed to search for neutrinoless double beta decay of $^{76}$Ge. The ${\rm D{\scriptsize EMONSTRATOR}}$ consisted of two modules of p-type point-contact germanium detectors operating at the 4850’ level of the Sanford Underground Research Facility in Lead, SD. The experiment recently concluded its primary physics data taking campaign spanning 2015 to 2021, and released final results this summer (2022). This full 65 kg-yr exposure achieves a world leading energy resolution of 2.5 keV FWHM and one of the lowest background indices at the double beta decay Q-value, with a competitive half-life lower limit of 8.3e25 yr (90% C.L.). The low backgrounds, low-energy thresholds, and excellent energy resolutions also enable competitive searches for double beta decay to excited states and beyond the Standard Model (BSM) physics. Over its lifetime, ${\rm M{\scriptsize AJORANA}}$ has validated key technologies for the next-generation 76Ge experiment LEGEND. In this talk, we present the final results from the ${\rm M{\scriptsize AJORANA}}$ ${\rm D{\scriptsize EMONSTRATOR}}$, highlighting particularly the improved limit on neutrinoless double beta decay of 76Ge and recently-released searches at low-energy for BSM physics.
Physics at High Energies
The presence of a non-baryonic Dark Matter (DM) component in the Universe is inferred from the observation of its gravitational interaction. If Dark Matter interacts weakly with the Standard Model (SM) it could be produced at the LHC. The ATLAS experiment has developed a broad search program for DM candidates in final states with large missing transverse momentum produced in association with other particles (light and heavy quarks, photons, Z and H bosons, as well as additional heavy scalar particles) called mono-X searches. The results of recent searches on 13 TeV pp data, their interplay and interpretation will be presented.
Dark matter produced via a strongly-coupled hidden sector can produce a wide array of signatures in detectors. In particular, in a model where the standard model couples to the dark sector via a leptophobic Z' mediator, the decay of the Z' mediator would yield jets that consist of partly visible and dark matter. The signature in a detector of such a 'semi-visible jet' is a jet aligned with missing transverse energy - a signature that is explicitly vetoed in most dark matter searches. CMS has recently published a search for semi-visible jets, the first of its kind at hadron colliders.
Dark matter may consist of feebly interacting massive particles (FIMPs) that have never thermalized with the cosmic plasma. Their relic density is successfully achieved through the freeze-in mechanism for a wide range of dark matter mass, significantly expanding the model space to be tested compared to other production mechanisms. However, testing the tiny couplings required by freeze-in is challenging. In this talk, I will show that FIMPs can be probed by LHC searches for new physics in mono-jet events with large missing energy. I will present a "gluophilic" $Z'$ portal model, in which gluon self-annihilation produces FIMPs in the early universe and also nowadays at colliders. Future mono-jet searches by LHC Run-3 might discover new physics accounted for FIMPs with mass scale in the MeV-TeV range.
Experimentally, dark matter has not yet been observed, and there is not yet any evidence for non-gravitational interactions between dark matter and Standard Model particles. In this talk, I will briefly review dark matter searches at CMS with Run II through different approaches with a focus on model-independent and dark sector searches. Since dark matter particles themselves do not produce signals in the Large Hardon Collider (LHC) detectors, one way to observe them is when they are produced in association with visible standard model particles such as muons, making the CMS detector an excellent probe for exploring the dark sector. I conclude the talk with the results of our analysis of the dataset, corresponding to 59.7 fb$^{-1}$ of proton-proton collisions at $\sqrt{s} =$ 13 TeV recorded during 2018, wherein I interpret the model-independent results of the analysis in the context of a dark matter model, by setting 95\% upper exclusion limits on the parameters of the model.
Precision Physics at High Intensities
In this talk I will start by reviewing the current status of the so-called neutral $B$-anomalies, a set of measurements in channels mediated by the $b \to s$ transition and involving muons in the final states. Several of these measurements disagree with SM predictions, and are coherently hinting at the presence of LFUV NP coupled to muons. After introducing the main groups performing global fits in a model-indepented EFT approach, and reviewing the several aspect under which these fits differ among each other, I will present a comparison among the obtained results. This comparison highlights the robustness of such analyses, and shows how present data strongly prefers several simple NP scenarios over a SM description of data.
Charged lepton flavor violation refers to processes in which lepton family number is not conserved. Transitions among the $e$, $\mu$, and $\tau$ leptons without the emission of neutrinos --- not through the weak force –- would be unambiguous proof of a new force in nature outside the Standard Model. The discovery of the muon in 1937 immediately led to searching for the decay $\mu \rightarrow e \gamma$, hypothesizing that muon was an excited electron. The failure to find that transition ultimately led to the notion of two neutrinos. Muons are uniquely powerful tools in finding CLFV because we can make intense beams of muons. We have used three main modes in the search: the two decay modes$\mu \rightarrow e \gamma$, $\mu \rightarrow 3e$, and muon-electron conversion, $\mu^-N \rightarrow e^-N$. We discuss the status and prospects of experiments for all three of these modes at Fermilab, J-PARC, and PSI. We will briefly discuss two other transitions, $\mu^-N \rightarrow e^+N$ and muonium-antimuonium oscillations. We conclude with the long-term outlook for these searches.
The rate of semitauonic B decays has been consistently above theory expectations since these decays were first measured. Recently significant differences between the forward-backward asymmetry in $B\to D^{∗}e\nu$ and $B\to D^{*}\mu\nu$ were also reported. This talk presents recent results on lepton flavor universality tests from Belle II and LHCb.
The NA62 experiment at CERN collected world's largest dataset of charged kaon decays in 2016-2018, leading to the first observation of the ultra-rare K+ --> pi+ nu nu decay based on 20 candidates. Dedicated trigger lines were employed for collection of di-lepton final states, which allowed establishing stringent upper limits on the rates lepton flavor and lepton number violating kaon decays. The dataset is also exploited to search for production of light feebly interacting particles (such as heavy neutral leptons) in kaon decays. Recent NA62 results based on the 2016-2018 dataset, and the prospects of the NA62 experiment, are presented.
Quark Matter and High Energy Heavy Ion Collisions
Heavy-ion collisions at the LHC and RHIC create a large enough energy density to form a deconfined medium of strongly-interacting quarks and gluons called quark-gluon plasma (QGP). The properties of the QGP including its near-perfect hydrodynamic behavior arising from the interactions between elementary quarks and gluons are not very well understood. Jets have proven to be crucial probes of the QGP as they originate from partons that are produced in initial hard-scatterings in heavy ion collisions, and subsequently pass through and interact with the medium. A rich repository of jet measurements in heavy-ion collisions from LHC and RHIC experiments over the past decade have played an important role in characterizing the Quark-Gluon Plasma. Recent developments in jet constituent reconstruction and grooming techniques have enabled the measurement of jet substructure observables in heavy-ion collisions and compare them to baseline pp results. In this talk, I will present an overview of jet substructure measurements in heavy-ion collisions and their impact on furthering our understanding of the jet-QGP medium interaction mechanisms including the opportunities and challenges that lay ahead.
High energy partons lose energy when traversing the hot and dense medium produced in heavy-ion collisions. This results in a modification of the transverse momentum distribution of jets manifesting a phenomenon known as jet quenching. Early measurements have established in heavy ion collisions that jet quenching results in significant modifications to the transverse momentum balance of dijet pairs. Further differential measurements probe the nature of the asymmetric jet quenching observed and explore the role of path-length dependent energy loss. This talk will discuss insights gained from recent dijet measurements from both RHIC and the LHC.
Hard partonic scatterings serve as an important probe of quark-gluon-plasma (QGP) properties. The properties of jets and their constituents can provide a tool for understanding the partonic energy loss mechanisms. Low momentum jets offer a unique window into partonic energy loss because they reconstruct the partons which have lost a significant amount of energy to the QGP medium. The main difficulty in studying low momentum jets in heavy ion collisions is the presence of a significant uncorrelated background of low momentum hadrons from soft processes. One way to deal with this background is to use jet-hadron correlations to fit and subtract the soft, flow-modulated background. This technique allows measurements of the near and away side yields. We present constituent yields for Pb--Pb collisions at √sNN = 5.02 TeV. These yields are a measurement of the raw fragmentation function. We discuss prospects for unfolding the distributions of yields to get a corrected fragmentation function for low jet momenta.
Dileptons are a crucial probe of the strongly interacting matter created in ultra-relativistic heavy-ion collisions. Leptons are produced during the whole evolution of the created matter and can traverse the medium with minimal interactions. Different kinematics of dilepton pairs (mass and transverse momentum ranges) can selectively probe the properties of the formed matter throughout its entire evolution. In the low invariant mass range (M_{ll} < 1.1 GeV/c2), vector meson in-medium properties may be studied via dilepton decays and may exhibit modifications related to possible chiral symmetry restoration. The di-lepton spectra in the intermediate mass range (1.1 < M_{ll} < 3.0 GeV/c2 ) are expected to be directly related to the thermal radiation of the Quark-Gluon Plasma. In this talk, I will review the recent measurements of dileptons in heavy ion collisions. Future perspectives will also be discussed.
QCD phase structure under magnetic field is a hot issue. On the hardonic side, Skyrme model with gauged Wess-Zumino Witten term is one of the simple low energy effective theory featuring chiral anomaly. Within such framework we investigate how an external magnetic field deforms the Skyrmion while preserving the homotopy. The Skyrme crystal constituted by multiple such magnetized Skyrmions provides us insights of the ground state of nuclear matter in strong magnetic field. We manifest the previously found \pi^0 domain wall structure can arise as one special class of solution to the Skyrme crystal. Another class of solution revealed by us feature both charged and neutral pions represents the inhomogenous baryonic phase. We establish the thermodynamics and phase diagram of these two classes of hardronic structure, which uncovers the underlying topological transmutation between $\pi^3(SU(2))$ and $\pi^1(U(1))$.
Nuclear Forces and Structure, NN Correlations, and Medium Effects
Neutron-rich nuclei near the limits of nuclear stability are one of the main areas of study at the Facility for Rare Isotope Beams (FRIB). These systems exhibit features common to all open quantum systems due to their weakly bound or unbound character, and also reveal interesting information about the nuclear interaction due to their extreme neutron-to-proton ratios and emergent behaviors. This is particularly visible in the so-called island of inversion (IOI) around Z=10 and N=20 where nuclear structure deviates from the standard shell model predictions due to deformation and continuum effects. Recently, two experiments on the neutron-rich isotopes 28,29F have revealed an unexpectedly large influence of continuum effects which effectively extends the IOI to these nuclei. In this work, I will discuss the mechanisms leading to these observations using state-of-the-art large-scale shell model calculations including continuum states and based on a core of 24O and an effective two-body interaction with a minimal number of adjustable parameters. I will also present new predictions in the isotopes 25-33F to motivate future experiments at FRIB.
CARIBU (CAlifornium Rare Isotope Breeder Upgrade) has been operating at the Argonne National Laboratory’s ATLAS facility for over a decade, and it is able to provide neutron-rich isotopic beams harvested from the fission fragment yield following the decay of a 252Cf source of ~1 Ci. These isotopes can be transported to a low-energy experimental hall and their ground state and decay properties studied, or they can be sent to an EBIS ion-source and reaccelerated by ATLAS and delivered to the various target stations. A robust program of research has utilized this facility over the last 10 years, concentrating on precision mass measurements, decay studies and Coulomb excitation measurements of re-accelerated beams. The program has been limited in available beam intensities due to targetry issues involving the 252Cf source. An upgrade to the facility is now underway to increase the radioactive beam capabilities of the ATLAS/CARIBU accelerator facility by the installation of a new source of fission fragments in CARIBU to provide reliably more intense beams of short-lived neutron-rich isotopes. These isotopes will be obtained from the neutron-induced fission of 235U in a thin foil located in a large gas catcher from which the radioactive ions will be extracted and transferred to the EBIS charge breeder before acceleration in the ATLAS superconducting linac. The technique keeps the fast, universal, and efficient features of CARIBU while removing the difficulties associated with obtaining a thin 252Cf source. It will increase the accelerated neutron-rich beam intensities by 10x due to increased fission yield into the gas catcher. This upgrade will enhance the reach of ATLAS/CARIBU and its world-unique capabilities to study neutron-rich nuclei. It will also help advance technologies critical for the FRIB facility. In this presentation, the facility as it now stands and how it will transform will be reviewed. In addition, highlights from the physics program will be given as well as examples of measurements which will be possible once the upgrade in completed will be presented.
The Association for Research at University Nuclear Accelerators (ARUNA; http://aruna.physics.fsu.edu) is an association of 13 university-based accelerator laboratories in the United States and the scientists performing research at them. Three ARUNA laboratories have the capability to produce rare-ion beams. Other ARUNA laboratories have developed unique capabilities in mono-energetic neutrons and high-intensity mono-energetic photon beams. ARUNA facilities are also characterized by their flexibility in performing long-term experiments or pursuing programs that are not possible within the environment of the national user facilities.
Scientists at the university-based ARUNA laboratories pursue research programs in nuclear astrophysics, low-energy nuclear physics, fundamental symmetries, and a rapidly growing number of nuclear physics applications, both at their own facilities and at user facilities, such as FRIB, ANL and others. Stable beam experiments at ARUNA labs complement the RIB studies at both ARUNA and user facilities. Detector development performed at ARUNA facilities is important for a wide array of experimental programs. Additionally, ARUNA facilities involve lots of students since they are based at Universities, so they are important for development of the workforce of the future.
A major focus of our group over the past decade has been the study of the continuum structure of p-rich light nuclei using the invariant-mass technique. This effort has led to the discovery of 7 new isotopes beyond (sometime well beyond) the proton drip line. Just as important are the finding of new resonances in previously known nuclei and parameter determination, or refinement, of resonances already known. Some of the more interesting results (e.g. finding of several near threshold states, fission of 16O, and fixing 0+2, and the rotational band built on it, in 10C) will be mentioned. This effort also prompted us to form a collaboration to resolve the 55-year old question of the cross section for nucleon induced inelastic deexcitation of the Hoyle state, a path parallel to EM decay. In the process of executing this program, we appreciated that we can offer a qualifier to the worn adage in quantum mechanical barrier penetration that the action (the forbidden momentum-distance area of a potential, made unit less by dividing by hbar) cannot be decomposed to inform on the shape of the barrier traversed.
Neutrino Masses and Neutrino Mixing
Neutrinos can escape dense environments, otherwise opaque to photons, and travel cosmic distances unscathed by background radiation or magnetic fields. They are ideal cosmic messengers and present a unique insight into the most energetic and enigmatic environments in the Universe. With the IceCube’s discovery of the high-energy cosmic neutrino flux, we have embarked upon a new era of high-energy physics and astrophysics with neutrinos. High-energy neutrinos can uncover the whereabouts of cosmic accelerators and present a unique opportunity to test fundamental particle physics. In this talk, I will discuss the recent developments in the observation of high-energy cosmic neutrinos and highlight the opportunities offered by the observables of cosmic neutrinos to probe for physics beyond the Standard Model in the neutrino sector.
When the neutrinos are at high densities, the neutrino-neutrino coherent forward scattering may lead to collective flavor oscillations. The evolution of these oscillations becomes a time-dependent quantum many-body problem. The computational complexities due to the exponential increase in the Hilbert space with the increase in the number of particles put limitations on how many neutrinos we can consider in our system of interest. To solve this many-body problem for a large number of neutrinos, the mean-field approximation can be quite helpful. However, this approximation does not provide any information on the correlations between neutrinos resulting from the two-body interaction. Therefore, we should seek the other numerical methods based on some approximations but still involve the correlations between neutrinos. In that direction,
we explore the tensor network methods to investigate the evolution of collective neutrino flavor oscillations. In particular, we employ the time-dependent variational principle method [1]. In this talk, I will discuss the comparison between different numerical approaches in terms of time
and resource complexities. In the case of tensor network methods, we see a significant reduction in the complexities in specific conditions.
Neutrinos in core-collapse supernovae are the main carriers of energy and lepton number, and therefore play an important role in the explosion mechanism as well as in the synthesis of nuclides in these environments. In the aftermath of a supernova explosion, neutrino-induced heating drives outflows of baryonic matter from the surface of the nascent neutron star. The physical characteristics of these outflows, such as expansion timescale, entropy, and electron fraction, can significantly impact the synthesis of proton-rich isotopes via the $\nu p$-process. This could be of much relevance to a long-standing problem in nuclear astrophysics, pertaining to the origin of certain proton-rich nuclides in nature: $^{92,94}$Mo and $^{96,98}$Ru. In particular, self-consistently modeled subsonic outflows from explosions of massive progenitors can be shown to furnish $\nu p$-process yields consistent with observed Mo and Ru abundances. These isotopic yields can also be directly influenced by neutrino flavor mixing in the vicinity of the neutron star. In this talk, we examine this interplay between matter outflows, neutrino mixing, and nucleosynthesis in core-collapse supernovae.
Neutrino-induced coherent pion production is a significant background for
electron neutrino appearance and muon neutrino disappearance in neutrino
oscillation experiments. MINERvA has measured the cross sections of the charged
current channel simultaneously in hydrocarbon (CH), graphite (C), iron (Fe) and
lead (Pb), which exceed the model predictions at multi-GeV $\nu_{\mu}$ energies
and at produced pion energies greater than 1 GeV and angles less than 10
degrees. Measurements of the cross-section ratios of Fe and Pb relative to CH
reveal the effective A-scaling to increase with increasing neutrino energy,
evolving from an approximate A$^{1/3}$ scaling at few GeV to an approximate
A$^{2/3}$ scaling for neutrino energies greater than 10 GeV. Cross sections for
$Q^{2}$, $E_{\mu}$ and $\theta_{\mu}$ were also obtained.
The observation of neutrinoless double beta decay in the next generation of experiments would reveal that lepton number is violated and that neutrinos are Majorana particles. Such a discovery will have far reaching implications, shedding light on the mechanism of neutrino mass generation, and giving insight on leptogenesis scenarios for the generation of the matter-antimatter asymmetry in the Universe. Double beta decay experiments are sensitive to a variety of lepton-number-violating scenarios, so that their interpretation relies on having a general and flexible theoretical framework, and on the accurate calculation of the hadronic and nuclear input arising in different mechanisms. In this talk, I will review recent progress in the development of an Effective Field Theory approach to neutrinoless double beta decay, from the electroweak scale all the way down to the typical scales of nuclear physics.
Particle and Nuclear Astrophysics
The IceCube Neutrino Observatory is a cubic kilometer detector located deep in the Antarctic ice, which has been operating in its full configuration since 2010. In 2013, IceCube discovered a diffuse flux of astrophysical neutrinos in the range of TeV to PeV energies. Since this discovery, there have been large efforts and gains in trying to: better understand the spectral shape of the flux, find the flavor composition of the flux, and identify the astrophysical sources contributing to the flux. In this talk, I will summarize the progress and latest results of these efforts made by the IceCube Collaboration.
QCD, Hadron Spectroscopy, and Exotics
Using data samples with a total integrated luminosity of more than 20 fb^-1 at center-of-mass energies between 4 and 5 GeV, charmonium(-like) states can be investigated in high detail with the BESIII experiment. Here, we will present past accomplishments and recent highlights, including studies on a Zcs candidate, cross section measurements of both hidden- and open-charm production and searches for new decay modes of the X(3782).
Results of the first global and unitary analysis of e+e- to b b-bar are presented. We find strong evidence for the new Upsilon(10750). Branching fractions are found to deviate significantly from older results. Implications of this for modelling are discussed.
Accessing the hadron spectrum from Quantum ChromoDynamics (QCD) poses several challenges given its non-perturbative nature and the fact that most states couple to multi-particle decay modes. Although challenging, advances in both theoretical and numerical techniques have allowed us to determine few-body systems directly from QCD. A synergistic approach between lattice QCD and scattering theory offers a systematic pathway to numerically compute properties such as the hadron spectrum from first principles. I will present an overview of this program, and discuss developments in determining three-body scattering processes and electroweak transitions of multi-hadron systems. These techniques allow us to push the boundaries of resolving the few-body problem in spectroscopy, and gives us insight into the structure of hadrons as the emergent phenomena of QCD.
We construct the light-front wavefunctions (LFWFs) of charmonium and bottomonium states on a small-sized basis function representation. In this work, we modeled the LFWFs for four charmonium states and three bottomonium states, $\eta_c$, $J/\psi$, $\psi'$, and $\psi(3770)$,as well as $\eta_b$, $\Upsilon$, $\Upsilon(2s)$, based on a set of orthonormal basis functions.The basis functions are eigenfunctions of an effective Hamiltonian, which has a longitudinal confining potential in addition to the transverse confining potential from light-front holographic QCD. We employ the experimental measurements of heavy quarkonium decay widths as well as input from NRQCD to determine the basis function parameters and superposition coefficients.
We study the features of those heavy quarkonium states using the obtained wavefunctions, including charge radii and parton distribution functions. Additionally, we use the vector meson LFWF to calculate the meson production in diffractive deep inelastic scattering and ultra-peripheral heavy-ion collisions at LHC, and the $\eta_c$ LFWF to calculate its diphoton transition form factor. Both results show agreement with experiments.
Heavy Flavors and the CKM Matrix
The CKM angle gamma determination through the tree-level is a standard candle measurement of CP violation in the Standard Model.
A new combination of all LHCb measurements is performed. A precision below four degrees is obtained, which dominates the world average.
The measurements on the precise determination of the CKM matrix elements Vcb and Vub whose ratio determines the length of the left side of the Unitarity Triangle are performed. The recent LHCb results on related CKM measurements and parameters are presented. Measurements are performed using the data sample collected with the LHCb detector corresponding to an integrated luminosity of 9fb-1.
We present preliminary lattice QCD results from the HPQCD collaboration for the $B\to D^*$ form factors, including tensor form factors. We use these results to construct the differential decay rate, which we compare directly to experimental data. We also present a 'lattice only' determination of the ratio, $R(D^*)=\Gamma(B\to D^*\tau\overline{\nu}_\tau)/\Gamma(B\to D^*\mu\overline{\nu}_\mu)$, as well as a model-independent determination of the CKM matrix element $|V_{cb}|$.
Precision Physics at High Intensities
For years, it was agreed that the radius of the proton was $0.88$ fm. A 2010 measurement using a new muonic-hydrogen spectroscopy technique reported a result of $0.84$ fm, a $5\sigma$ discrepancy with the the accepted value, launching what has come to be known as the ``proton radius puzzle''. A flurry of explanations emerged in the aftermath, ranging from new physics to incorrect analysis techniques. The 2016 PRad experiment at JLab, using a novel magnetic-spectrometer-free setup, measured the proton radius to be $0.831\pm0.014$ fm, consistent with the muonic hydrogen result and $2.7\sigma$ smaller from the combined results of all past $e-p$ scattering measurements. In this talk, I will discuss the PRad result and the upcoming PRad-II experiment that aims to achieve nearly $4$ times precision and record data at the lowest $Q^2$ ever achieved in lepton scattering ($10^{-5}$ GeV$^2$).
In this talk, I will review the lattice QCD calculation of the electric and magnetic electric form factors and the extraction of the proton charge radius. I will use the recent work done by the NME collaboration [1], and updates to it (preliminary results with improved data sets) to illustrate the issues. These high statistics lattice QCD calculations, show that the electric and magnetic electric form factors are consistent with the Kelly parametrization of the experimental data over the range 0.04≲Q^2≲1.2GeV but have larger uncertainties than the experimental data. A heuristic parametrization of the form factor for phenomenological analyses will be presented. Last, I will compare these results with those obtained by other lattice QCD collaborations.
[1] PRD 105 054505 (2022)
Quark Matter and High Energy Heavy Ion Collisions
The quark gluon plasma (QGP) created in the Ultrarelativistic heavy-ion collisions behaves like a near perfect fluid with a small specific shear viscosity. Due to its transience and microscopic size, the QGP cannot be observed directly, but only through the particles it emits.
The JETSCAPE framework is a multistage framework that incorporates multiple models, each effective at an individual scale range [1,2]. Within the JETSCAPE framework, we will discuss about the extraction of the transport coefficients of the QGP by a model-to-data comparison with Bayesian inference. Specially, we will present an extensive, comparative study that explores the properties of the strongly-coupled quark-gluon plasma with a multistage model of heavy ion collisions that combines the TRENTO initial condition ansatz, free-streaming, viscous relativistic hydrodynamics, and a relativistic hadronic transport with deuteron evolution. Deuteron production shows sensitivity to the hydrodynamic model — in particular to bulk viscosity [3]. Accounting for the different sets of model assumptions in the model analysis and comparing various flow observables, including the related observables for deuterons, Bayesian inference provides the most reliable phenomenological constraints to date on the QGP viscosities.
[1] D. Everett et al. [JETSCAPE], Phys. Rev. C 103 (2021) no.5, 054904.
[2] D. Everett et al. [JETSCAPE], Phys. Rev. Lett. 126 (2021) no.24, 242301.
[3] D. Everett et al. [JETSCAPE], [arXiv:2203.08286 [hep-ph]].
The creation of a Quark-Gluon Plasma (QGP) during heavy-ion collisions constitute a unique opportunity to study strong interactions under extreme conditions. Therefore, the JETSCAPE collaboration was started with the purpose of developing a multistage framework capable of combining different models at each stage, in order to study the evolution of jets and high-pT probes during heavy-ion collisions. Work is ongoing to upgrade the framework to be able to incorporate small systems such as pA and pp experiments. We present a two-stage approach for these small systems, where a 3D MC-Glauber model is used to describe event-by-event geometric configurations of the colliding system, while the hard scatterings are obtained from PYTHIA and propagated backward in space-time using a new iMATTER module to obtain their initial energies and momenta before the initial-state showers. The initial energies are then subtracted from the incoming colliding nucleons, leaving less energy for the soft-particle production, and leading to a correlation between jets and the multiplicity of small systems.
How collectivity originates and evolves in the collisions of small size systems is a highly debated topic in the heavy ion community. The evolution may be associated with both hydrodynamic and non-hydrodynamic modes. Furthermore, the uncertaities of initial geometry due to the internal nucleonic structure and its fluctuations will significantly degrade the predictive power of the available dynamical evolution models.
In this talk, we will present measurements of flow harmonics ($v_2$, $v_3$) in $p$+Au, $d$+Au and $^3$He+Au collisions at 200GeV. Taking the advantage of the wide mid-rapidity coverage of Time Projection Chamber (-1$<\eta <$1) in STAR, the flow coefficients are extracted via correlations of di-hadrons both in the mid-rapidity and $|\Delta\eta|>$ 1.0. It will avoid the longitudinal dynamics contribution and provide crucial apples-to-apples comparisons with available model calculations, since most of them are boost-invariant.
Such measurements will also provide useful information to understand the effect of nucleonic or sub-nucleonic fluctuation on the initial geometry in the small size colliding systems.
This talk presents an overview of recent results on collectivity in small collision systems. At LHC energies, the measurements involves light quark hadrons, strange, charm and bottom hadrons in pp, pPb, and ultra-peripheral PbPb and pPb collisions. The collectivity results for charged hadrons from the PHENIX collaboration are also presented in pAu, dAu and 3HeAu collisions. These measurements provide new insight into the origin of collectivity in small systems.
Quantum Chromodynamics allows for the formation of parity-odd domains inside the medium produced in heavy-ion collisions associated with a net chirality of the quarks. Thus one local $CP$ violation phenomenal, Chiral Magnetic Effect (CME), is allowed in the heavy-ion collisions. In the past two decades, many experimental researchers are looking for such an effect with different observables and techniques. Although some non-zero results are observed at both RHIC and LHC energies, looking for conclusive evidence of CME is still going on, which requires careful consideration of the charge-dependent backgrounds.
Recently, the STAR experiment has reported their latest studies at both top and lower RHIC energies and try to quantify the possible signal. In this talk, I will present my understanding of the recent studies of the Au+Au collisions and isobar collisions. Some possible future experimental outlooks will also be briefly discussed.
Nuclear Forces and Structure, NN Correlations, and Medium Effects
Neutrinoless double beta decay ($0\nu\beta\beta$) is a hypothetical process that two neutrons in a nucleus simultaneously decay to protons, emitting two electrons but no anti-neutrinos. Searching for $0\nu\beta\beta$ is currently considered the only viable experimental technique to test the Majorana nature of neutrinos. As the $0\nu\beta\beta$ process violates lepton number conservation, its observation would provide major new insights to the beyond-the-Standard-Model (BSM) physics.
In this talk, a summary of the current and future large scale experiments searching for $0\nu\beta\beta$ is provided. In particular, a detailed description of the LEGEND experiment is provided. This ton-scale $^{76}$Ge-based $0\nu\beta\beta$ experiment has a discovery potential for $0\nu\beta\beta$ half-life beyond $10^{28}$ years. Other searches for BSM physics accessible to large-scale $0\nu\beta\beta$ experiments such as LEGEND will also be discussed.
The COHERENT collaboration operates a suite of neutrino detectors that are located in a basement hallway at the Spallation Neutron Source, at Oak Ridge National Laboratory. The detectors in “Neutrino Alley” search for neutrino-nucleus interactions from Coherent Elastic Neutrino-Nucleus Scattering as well as higher energy Charged and Neutral current inelastic measurements. The results of these experiments have implications for understanding coupling strengths, searches for physics beyond the standard model, as well as neutrino-nuclear astrophysics. I will report on the current status of these measurements, and planned upgrades.
We perform a universal fit to all available electron scattering data on Carbon and Oxygen and extract the best determination of the Inelastic Coulomb Sum Rule (CSR) as a function of momentum transfer q. The longitudinal Quasielastic (QE) cross section is suppressed by a larger factor then expected from Pauli blocking only. We provide a parameterization of this “extra suppression” for use in electron and neutrino Monte Carlo generators. The contribution of nuclear excitations to CSR as a function of q can be as high as 30% and must be accounted for . The extracted CSR values for Carbon are in good agreement with the “first principle Green’s function MC” calculation of Lavato et al. Phys. Rev. Lett. 117, 082501 (2016). The extracted CSR values for Oxygen are in agreement with the Coupled Custer calculation of J. E. Sobczyk et al. .Phys. ReV. C 102, 064312 (2020))
Parton and Gluon Distributions in Nucleons and Nuclei
I will review recent results for fragmentation functions using the Monte Carlo fitting approach of the Jefferson Lab Angular Momentum (JAM) collaboration
Both SIDIS and e+e- annihilation provide clean and complimentary environments to study hadronization. While the e+e- annihilation cross-section is independent of a non-perturbative partonic initial state, SIDIS data enables more sensitivity to the flavor dependence of the hadronization process.
With record setting datasets being collected in SIDIS by the CLAS12 experiment and in e+e- by the Belle and Belle II experiment, new opportunities to study the dynamics of hadronization at intermediate energies arise. This talk will discuss recent results and future plans in di-hadron correlation measurements and hyperon production at CLAS12. We will then focus on recent measurements of fragmentation functions at Belle and a roadmap for precision hadronization measurements at Belle II recently laid out in a snowmass whitepaper.
The lepton-jet momentum imbalance in deep inelastic scattering events offers a useful set of observables for unifying collinear and transverse-momentum-dependent frameworks for describing high energy Quantum Chromodynamics interactions. A recent first measurement was made [1] of this imbalance in the laboratory frame using positron-proton collision data recordedf with the H1 experiment at HERA in the years 2006-2007. Using a new machine learning method, the measurement was performed simultaneously and unbinned in eight dimensions. The first results were presented as a set of four one-dimensional projections onto key observables. This work extends over those results by making use of the multi-differential nature of the unfolded result. In particular, distributions of lepton-jet correlation observables are studied as a function of the kinematic properties of the scattering process, i.e. as a function of the momentum transfer $Q^2>150$ GeV$^2$ and the inelasticity $0.2< y< 0.7$.
H1prelim-22-031
[1] PRL 128 (2022), 132002 [arxiv:2108.12376]
Gluons constitute the bulk of the mass of the visible universe and play a major role in determining the fundamental properties of protons, neutrons and other hadrons. The one-dimensional structural properties of hadrons are partly encoded in parton distribution functions (PDFs), which capture their longitudinal momentum structure. Our knowledge of the gluon PDF of the nucleon has been significantly improved by the wealth of data from the Large Hadron Collider, but many aspects of gluon structure are still unclear. I summarise recent attempts to understand the gluon structure of hadrons directly from lattice quantum chromodynamic (QCD), the numerical solution of QCD on a Euclidean spacetime lattice, and outline some of the challenges involved in these first-principles calculations.
Jefferson Lab is facing a time of change, unprecedented since the founding of the Lab, by diversifying and expanding its scientific mission, in partnership with DOE-SC. Over the next decade Jefferson Lab will be delivering on the 12 GeV program while laying the groundwork for CEBAF’s future role in Nuclear Physics. Upgrades for higher luminosity, polarized and unpolarized positron beams, and higher energies up to 24 GeV are envisioned.
To probe the science that would be opened up by a higher energy electron beam (~20-24 GeV), a series of summer workshops has been organized jointly between the laboratory and the Jefferson Lab Users Organization. The workshops aim to identify key measurements that are not possible to access at 12 GeV and that initially utilize largely existing or already-planned Hall equipment, and that leverage the unique capabilities of luminosity and precision possible at Jefferson Lab in the EIC era.
In the presentation the initial investigation of these opportunities at higher energy CEBAF will be given.
Particle and Nuclear Astrophysics
Announcing the dawn of a new era of multi-messenger astrophysics, the gravitational wave event GW170817 – involving the collision of two neutron stars – was detected in 2017. In addition to the gravitational wave signal, it was accompanied by electromagnetic counterparts providing new windows into the different physics probed by the system. Since then, several gravitational wave events involving neutron stars have been discovered, with many more expected over the next years.
In order to understand and interpret the physics of these events, it is necessary to model the intricate dynamics of such systems before, during and after the merger, including the amplification of strong magnetic fields and the formation of hot and dense nuclear matter. Due to its strong non-linear nature, a modeling of the post-merger phase will only be possible with cutting-edge numerical approaches that combine strong gravity, nuclear physics and plasma astrophysics.
In this talk, I will discuss recent advances in the multi-physics modeling of a neutron star coalescence. With the help of several examples, I will show how future gravitational wave detections of the post-merger phase might allow to systematically uncover the properties of hot dense matter. I will further highlight the connection of neutron star mergers and heavy-ion collisions, with a particular emphasis on the deconfinement phase transition. Along those lines, I will also show how neutrino-driven viscosity can naturally arise during the collision. I will conclude by discussing how such a multi-physics approach will enable a next generation modeling of the engines of multi-messenger gravitational events.