Bulletin of the American Physical Society
Fall 2022 Meeting of the APS Division of Nuclear Physics
Volume 67, Number 17
Thursday–Sunday, October 27–30, 2022; Time Zone: Central Daylight Time, USA; New Orleans, Louisiana
Session DC: Hadronic Physics I |
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Chair: Dipangkar Dutta, Mississippi State Univ Room: Hyatt Regency Hotel Celestin A |
Friday, October 28, 2022 8:30AM - 8:42AM |
DC.00001: Towards a Cross Section Measurement of Deeply Virtual Neutral Pion Production at CLAS12 Robert E Johnston Deeply virtual exclusive reactions provide unique channels to study both transverse and longitudinal properties of the nucleon simultaneously, allowing for a 3D image of nucleon substructure. This presentation will discuss work towards extracting an absolute cross section for one such exclusive process, deeply virtual neutral pion production, using 10.6 GeV electron scattering data off a proton target from the CLAS12 experiment in Jefferson Lab Hall B . This measurement is important as exclusive meson production has unique access to the chiral odd GPDs, and is also a background for other exclusive processes such as DVCS, making the determination of this cross section crucial for other exclusive analyses. |
Friday, October 28, 2022 8:42AM - 8:54AM |
DC.00002: Physics informed deep learning models for exclusive reactions Brandon Kriesten, Manal Almaeen, Jake Grigsby, Yaohang Li, Huey-Wen Lin, Simonetta Liuti
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Friday, October 28, 2022 8:54AM - 9:06AM |
DC.00003: Exclusive Phi Electroproduction Cross Section Measurement off the Proton at CLAS12 Patrick H Moran A central goal of the Jefferson Lab 12 GeV upgrade is the imaging of the 3-dimensional internal structure of the nucleon at high resolution. The exclusive $\phi$ electroproduction process off of a hydrogen target probes the proton's gluon GPD in the valence region, providing insight into the spatial distribution of the gluons within the proton. An update is given on the exclusive $\phi$ meson electroproduction cross section measurement at 10.6 GeV by Jefferson Lab's CLAS12 detector. |
Friday, October 28, 2022 9:06AM - 9:18AM |
DC.00004: Polarization observables for DVCS and TCS experiments Philip Velie, Brandon Kriesten, Zaki Panjsheeri, Simonetta Liuti Imaging the dynamic parton substructure of the nucleon is a fundamental goal of many nuclear physics programs at both Jefferson Lab and the future electron-ion collider (EIC). Deeply virtual exclusive scattering experiments have been identified as the cleanest probe of quark and gluon quantum correlation functions, the generalized parton distributions (GPDs). Critical to extracting information on hadron structure through GPDs is a global analysis of various exclusive reactions, such as deeply virtual Compton scattering and timelike Compton scattering. I will give some prospects for exclusive scattering polarization observables that are possible at an EIC/JLAB and the progress that has already been made in preparation for such programs. |
Friday, October 28, 2022 9:18AM - 9:30AM |
DC.00005: Hard exclusive π-Δ++ production off the proton with CLAS12 at JLAB Stefan Diehl Hard exclusive pion production is a well established tool to study Generalized Parton |
Friday, October 28, 2022 9:30AM - 9:42AM |
DC.00006: Dynamic imaging of quarks and gluons inside the proton Zaki Panjsheeri, Joshua Beethoven P Bautista, Adil Khawaja, Brandon Kriesten, Simonetta Liuti, Philip Velie We can gain insight into matter, charge, and radial distributions of the partons inside the nucleon using two-dimensional Fourier transforms of generalized parton distributions (GPDs). We perform such Fourier transforms in a dynamic scenario, including overlap of partons, which incorporates two-body densities, highlighting the possibility of gluon hotspots. Calculations were performed for several values of the momentum fraction X and the skewness ζ, which plays a significant role in shaping these distributions, and evolved using perturbative QCD from the initial scale Q0 to the scale of the data at 10 GeV2. |
Friday, October 28, 2022 9:42AM - 9:54AM |
DC.00007: Investigating Transversity with Hadrons in Jets at STAR James L Drachenberg The transversity distribution function is one of the fundamental pieces needed for a complete understanding of the structure of the nucleon. One way the STAR experiment accesses transversity is through the “Collins mechanism,” measuring spin-dependent azimuthal distributions of hadrons within jets from transversely polarized p+p collisions. STAR data probe transversity over a range of x similar to semi-inclusive deep inelastic scattering experiments but at much higher Q2. Furthermore, these data provide unique insight to the in-jet transverse momentum dependence of the Collins asymmetry, crucial for deepening our understanding of the Collins fragmentation function. The first observation of the Collins asymmetry at STAR was reported from data at √s = 500 GeV collected in 2011. In 2012 and 2015, STAR collected substantially more data at 200 GeV, allowing a far more detailed investigation of the Collins asymmetries and additional questions related to TMD evolution and factorization. In this presentation, the 200 GeV STAR Collins asymmetry results will be shown and discussed in context with the 500 GeV data and recent model calculations. |
Friday, October 28, 2022 9:54AM - 10:06AM |
DC.00008: Studying the flavor dependence of TMD fracture functions with CLAS12 Timothy Hayward We report the first measurements studying the flavor dependence of the double semi-inclusive deep inelastic scattering process, where one hadron is detected in the current-fragmentation region (CFR) and another in the target-fragmentation region (TFR). Observed non-zero $\sin \Delta \phi$ modulations, where $\Delta \phi$ is the difference of azimuthal angles of the hadrons, indicate that long range correlations exist between the spin and transverse momenta of hadrons produced simultaneously in the CFR and TFR and allow access to a leading-twist transverse-momentum-dependent fracture function describing longitudinally polarized quarks in an unpolarized nucleus. The data were taken with a 11~GeV longitudinally polarized electron beam incident on unpolarized liquid hydrogen and deuterium targets using the CLAS12~Spectrometer at Jefferson Lab. These data represent a significant extension over the first CLAS12 results, which were limited to the $ep \rightarrow e'p\pi^+X$ process. We now incorporate a factor of two times more proton target statistics, compare results for proton and deuterium targets in order to study the flavor dependence of fracture functions for the first time and include both $\pi^+$ and $\pi^-$ final state CFR hadrons in order to test the universality of the formalism and cross-check the results with separate channels that may be subject to different systematics. |
Friday, October 28, 2022 10:06AM - 10:18AM |
DC.00009: Generalized parton distributions through universal moment parameterization: zero skewness case YUXUN GUO, Xiangdong Ji, Kyle L Shiells We present a global analysis program for the generalized parton distributions (GPDs) based on conformal moment expansion. We apply the strategy of universal conformal moment parameterization to fit both the collinear parton distribution functions (PDFs) from phenomenology and generalized form factors from lattice calculations, and show that the parameterization is flexible enough to accommodate these constraints. In addition, we can also fit direct lattice calculations of GPDs from large-momentum effective theory. In this work we focus on the analysis of $t$-dependent PDFs which correspond to GPDs in the $\xi \to 0$ limit. The strategy also applies to the $\xi \not =0$ region with extra parameters, and therefore can be fitted to experimental observables in the future. With a demonstrative example of fitted GPDs, we show the quark transverse angular momentum densities of the proton as well as the impact parameter space distributions of quarks in both unpolarized and transversely polarized protons. |
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