Bulletin of the American Physical Society
88th Annual Meeting of the Southeastern Section of the APS
Volume 66, Number 16
Thursday–Saturday, November 18–20, 2021; University Center Club, Florida State University, Tallahassee, Florida
Session A05: Medium Energy Nuclear Physics |
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Chair: Volker Crede, Florida State University Room: West Ballroom |
Thursday, November 18, 2021 9:30AM - 10:00AM |
A05.00001: Diffractive and Tagging Processes in EIC Collider Experiment - ECCE Invited Speaker: Wenliang Li The Electron-ion Collider to be constructed at Brookhaven National Lab is considered to be the next generation "dream machine" in future QCD research. One of its main objectives is to provide answers to the many puzzles on the hadron structure raised by the recent studies at the Jefferson Lab and RHIC programs and unveil new information. The ECCE (EIC Collider Experiment) consortium, is developing a general purpose detector designed to meet the requirements and performance goals for the EIC physics program, as laid out by the EIC Yellow-Report. In this presentation, I will concentrate on the ongoing research efforts on the Diffractive and Tagging processes, whose goal is to study meson and hadron structures as well as explore new opportunities such as the electron heavy-ion diffractive scatterings using the integrated Far Forward detector system. [Preview Abstract] |
Thursday, November 18, 2021 10:00AM - 10:15AM |
A05.00002: Coordinate Space Representation of Quark and Gluon Generalized Parton Distribution Functions Zaki Panjsheeri, Philip Velie, Brandon Kriesten, Simonetta Liuti Two-dimensional Fourier transforms of generalized parton distributions (GPDs) provide insight into matter, charge, and radial distributions of the quarks and gluons inside the nucleon.~ ~We present an explicit calculation of such transforms in a spectator model framework using parametric analytic forms of GPDs, originally constrained using deeply virtual Compton scattering and lattice QCD data. ~Calculations were performed~for several values of the momentum fraction~X and~evolved using perturbative QCD from the initial scale Q$_{0}$~to the scale of the data.~ We studied the effect of evolution, the difference between matter and charge density in both the proton and the neutron, and the location of the gluon distribution relative to the valence quarks. [Preview Abstract] |
Thursday, November 18, 2021 10:15AM - 10:30AM |
A05.00003: Measurements of $\eta$ and $\omega$ Photoproduction Beyond The Nucleon Resonance Regime Tianqi Hu, Zulkaida Akbar, Volker Crede Measurements of light meson photoproduction are critical for understanding the underlying production mechanism in photon-nucleon interaction. At low energies, nucleon resonances have been extensively studied using techniques such as partial wave analysis. However, scarcities of cross section and polarization data over the photon energy range 3-6 GeV have thus far hindered our understanding of the transition from the nucleon resonance regime to t-channel Pomeron and Regge exchanges. In this talk, we will present recent measurements of $\eta$ and $\omega$ meson differential cross sections, and $\omega$ meson spin density matrix elements(SDMEs) from close to the production thresholds up to the t-channel regime using the data collected at Jefferson Lab during the CLAS g12 run period. The circularly-polarized $\omega$ SDMEs have been measured for the first time. The production mechanism will be discussed in comparison with various models. The $\eta$ and $\omega$ differential cross sections have been fairly well described by the $\eta$-MAID 2018 and Laget models, respectively. The flip-sign discrepancy of the $\omega$ SDME $\rho^{0}_{1-1}$ with the JPAC model implies the potential contribution of unnatural-parity exchanges is smaller than the previous model predicted. [Preview Abstract] |
Thursday, November 18, 2021 10:30AM - 10:45AM |
A05.00004: The Beam-Helicity Asymmetry in $\omega $ Photoproduction Shelby Arrigo, Volker Crede The spin-1 nature of the $\omega $ meson gives rise to additional spin observables, not accessible in spinless mesons.~ Data from the CLAS-g12 experiment at Jefferson Lab has been used involving a circularly polarized tagged photon beam and an (un)polarized proton target to extract the beam helicity asymmetry. This observable is an important component in the global effort of mapping the excited nucleon spectrum since the asymmetry allows one to learn about the intermediate states of the reaction where an $\omega $ meson can form in the decay of an excited nucleon state. The observable will help shed light on the spin orientation of the produced $\omega $ meson in the final state, which will provide insight into the inner workings of the nucleon resonances in the intermediate state. The helicity frame has been used, where the z axis is defined by the momentum axis of the $\omega $ meson in the overall center-of-mass frame. The first step in this analysis is to look at the asymmetry between different beam helicity states, and an extension of this data analysis will be to measure the asymmetry between orthogonal initial-proton polarization states (using longitudinally polarized protons) in an effort to extract the target asymmetry in this reaction. [Preview Abstract] |
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