Bulletin of the American Physical Society
APS April Meeting 2023
Volume 68, Number 6
Minneapolis, Minnesota (Apr 15-18)
Virtual (Apr 24-26); Time Zone: Central Time
Session LL01: V: Hadronic Physics I |
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Sponsoring Units: GHP Chair: Dien Nguyen, Jefferson Lab Room: Virtual Room 1 |
Tuesday, April 25, 2023 8:00AM - 8:12AM |
LL01.00001: Resumming Quark's Longitudinal Momentum Logarithms in LaMET Expansion of Lattice PDFs Yushan Su, Jack Holligan, Xiangdong Ji, Fei Yao, Jian-Hui Zhang, Rui Zhang In the large-momentum expansion for parton distribution functions (PDFs), the natural physics scale is the longitudinal momentum (p_{z}) of the quarks (or gluons) in a large-momentum hadron. We show how to expose this scale dependence through resumming logarithms of the type ln^{n}(p_{z}/μ) in the matching coefficient, where μ is a fixed renormalization scale. The result enhances the accuracy of the expansion at moderate p_{z}>1 GeV, and at the same time, clearly shows that the partons cannot be approximated from quarks with p_{z} ~ Λ_{QCD }which are not predominantly collinear with the parent hadron momentum, consistent with power counting of the large-momentum effective theory. The same physics mechanism constrains the coordinate space expansion at large distances z, the conjugate of p_{z}, as illustrated in the example of fitting the moments of the PDFs. |
Tuesday, April 25, 2023 8:12AM - 8:24AM |
LL01.00002: Nucleon quasi-parton distributions in the large N_{c} limit Asli Tandogan, Maxim V Polyakov, Hyeon-Dong Son In this talk, we present the nucleon quasi-parton distribution functions in the chiral quark soliton model. The derivation of a set of sum-rules depending on the velocity of the nucleon and on the Dirac matrix defining the distribution functions is demonstrated. We present numerical results for the isosinglet unpolarized distribution, in which we find that the anti-quark distribution breaks the positivity condition at nucleon velocities of v≈0.99(PN≈7.0MN) and smaller. For the isosinglet unpolarized case, we show that a large nucleon momentum is required for the quasi-parton distribution to get close enough to the usual parton distribution function. |
Tuesday, April 25, 2023 8:24AM - 8:36AM |
LL01.00003: GUMP program for GPD global analysis: quark GPDs from DVCS YUXUN GUO, Xiangdong Ji, Kyle L Shiells, M. Gabriel G Santiago, Jinghong Yang We present the first global analysis of generalized parton distributions (GPDs) combing lattice Quantum Chromodynamics (QCD) calculations and experiment measurements including global Parton Distribution Functions (PDFs), Form Factors (FFs) and Deeply Virtual Compton Scattering (DVCS) measurements. Following the previous work where we parameterize GPDs in terms of their moments, we extend the framework to allow for the global analysis at non-zero skewness. Together with the constraints at zero skewness, we fit GPDs to global DVCS measurements from both the recent JLab and the earlier Hadron-Electron Ring Accelerator (HERA) experiments with two active quark flavors and leading order QCD evolution. With certain choices of empirical constraints, both sea and valence quark distributions are extracted with the combined inputs, and we present the quark distributions in proton correspondingly. We also discuss how to extend the framework to accommodate more off-forward constrained beyond the small $xi$ expansion, especially the lattice calculated GPDs. |
Tuesday, April 25, 2023 8:36AM - 8:48AM |
LL01.00004: Effective field theory for the doubly charmed tetraquark Boris Gelman I will discuss an effective field theory for the doubly charmed tetraquark T_{cc}(3875)^{+} that was discovered by the LHCb collaboration in July 2021. The power counting in this effective field theory (EFT) is based on the fact that the energy of T_{cc}(3875)^{+ }is very close to the D^{*+}D^{0} threshold, and its decay width is very narrow due to the D^{0}D^{0}π^{+ }phase space suppression near the threshold. I use the EFT to describe the three-body decay rate of the doubly charmed tetraquark. |
Tuesday, April 25, 2023 8:48AM - 9:00AM |
LL01.00005: Hard exclusive π^{+} electro production off the proton in the GPD regime with CLAS12 Stefan Diehl Hard exclusive meson production is a well established tool to study the 3D nucleon structure in terms of the transverse position and the longitudinal momentum component of the partons. The QCD factorisation mechanism in the "nearly forward region" (t/Q² small) can be divided into a hard part, described by perturbative QCD (pQCD) and in two general structure functions, the GPDs for the nucleon and the pion distribution amplitudes (DAs), describing the complex non perturbative structure of these particles. The talk presents a measurement of single beam spin asymmetries to extract the polarized cross section ratio σ_{LT’}/σ_{0} from the hard exclusive π^{+} channel off the unpolarized hydrogen based on data taken with the CLAS12 spectrometer in hall B at Jefferson Lab. A detailed multidimensional study will be presented and discussed based on a comparison to theoretical models. |
Tuesday, April 25, 2023 9:00AM - 9:12AM |
LL01.00006: SBS-GMn Analysis Update Provakar Datta Nucleon elastic form factors help us understand the nucleon structure by probing its four-current distributions. But very little is known of the neutron's magnetic form factor, $G^{n}_{M}$, for $Q^2 > 4$ (GeV/c)$^2$. To shed some light in this area the SBS-$G_M^n$ experiment (E12-09-019) has run recently in Jefferson Lab's experimental Hall A and has made several high precision measurements of $G_M^n$ in the range $3 < Q^2 < 13.6$ (GeV/c)$^2$ using ``ratio" method. A huge effort of offline data analysis is ongoing since the experimental data taking has been finished in February, 2022. First pass cooking of the entire data set (≈ 2 PB of raw data) has been completed following offline calibration of the detectors. Although preliminary, comparisons of data and simulation are showing encouraging results which are worth sharing with the community. In this talk, I will present an update of SBS-$G_M^n$ analysis progress highlighting some of the interesting findings. |
Tuesday, April 25, 2023 9:12AM - 9:24AM |
LL01.00007: The generalized electromagnetic polarizabilities of the proton Hamza Atac, Nikos Sparveris, RUONAN LI, Mark Jones, Michael E Paolone |
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