Speaker
Description
High-energy electrons and photons serve as remarkably clean probes of hadronic matter, providing a microscope for examining the strong nuclear force. One of the most striking phenomena of Quantum Chromodynamics (QCD) is the formation of hadrons out of massless gluons and nearly massless quarks. This system of confined quarks and gluons exhibits the characteristic spectra of excited states, which are sensitive to the details of quark confinement. Probing this non-perturbative regime of QCD remains a challenge in hadron spectroscopy. The GlueX experiment in Hall D at Jefferson Lab has accumulated high-statistics samples of photoproduction data off the proton in recent years. In addition to conventional mesons (quark-antiquark) and baryons (three-quark), QCD also predicts so-called hybrid hadrons containing excited glue which contributes to the overall quantum numbers of the hadronic resonance. In particular, hybrid mesons can exhibit quantum numbers that are not possible for a conventional quark-antiquark system. To this end, photoproduction experiments are an important tool in the investigation of the hadron spectra and the way gluons contribute to the hadronic system. The main motivation of the GlueX experiment is to search for and study exotic hybrid mesons and the mapping of the lowest-mass hybrid-meson nonets. But GlueX will also be able to shed more light on the spectrum of strangeness −2 $\Xi$ baryons. Substantial data have also been collected on excited strange baryons (strangeness −1), e.g., for the Λ(1405) and Λ(1520), along with the data for $\Xi$ baryons in an experimental hyperon program. In this talk, I will give an update on recent results from the GlueX experiment at Jefferson Laboratory.
