Conveners
EW: Tests of Symmetries and the Electroweak Interaction: neutron EDM
- Stéphanie Roccia
- Nadia Fomin (University of Tennesee - Knoxville)
EW: Tests of Symmetries and the Electroweak Interaction: Tests of T reversal
- Stéphanie Roccia
- Nadia Fomin (University of Tennesee - Knoxville)
EW: Tests of Symmetries and the Electroweak Interaction: Beta decay
- Stéphanie Roccia
- Nadia Fomin (University of Tennesee - Knoxville)
EW: Tests of Symmetries and the Electroweak Interaction: neutron Beta decay
- Nadia Fomin (University of Tennesee - Knoxville)
- Stéphanie Roccia
Description
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...
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,...
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...
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....
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...
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...
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...
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...
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...
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...
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...
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 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...
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...
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...
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...
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...
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...
Precision measurements of observables in nuclear and neutron beta decay to provide important information on the structure and symmetries of the weak interaction at low energy. Among the empirical foundations of the electroweak Standard Model the assumptions of maximal parity violation, vector and axial-vector character and massless neutrinos are directly related to the experiments performed...
The TRIUMF ultracold advanced neutron (TUCAN) electric dipole moment (EDM) experiment aims to constrain the neutron's electric dipole moment by an order magnitude over the current sensitivity. The experiment employs a magnetically shielded Ramsey Resonance based EDM apparatus employing ultracold neutrons from a spallation based isopure Helium-II UCN source, currently under construction at...
