Bulletin of the American Physical Society
APS April Meeting 2022
Volume 67, Number 6
Saturday–Tuesday, April 9–12, 2022; New York
Session L07: Nucleon Structure and Nucleon SpinRecordings Available
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Sponsoring Units: GHP Chair: Simonetta Liuti, University of Virginia Room: Salon 4 |
Sunday, April 10, 2022 3:45PM - 4:09PM |
L07.00001: GHP Dissertation Award: Hadronic Processes on the Lattice in the Era of Precision Flavor Physics Invited Speaker: Davide Giusti The leading uncertainty in obtaining precise fundamental information from Particle Physics experiments is due to the difficulty of quantifying non-perturbative strong-interaction effects. |
Sunday, April 10, 2022 4:09PM - 4:21PM |
L07.00002: Measurement of the two photon exchange on the neutron with Super BigBite spectrometer in Hall A at Jefferson Lab Eric Fuchey The nTPE experiment which will run in January of 2022 in Jefferson La Hall A |
Sunday, April 10, 2022 4:21PM - 4:33PM |
L07.00003: Test Beams for a Proposed Two-Photon Exchange Experiment (TPEX) at DESY Patrick H Moran Recent elastic lepton-proton measurements of the proton form factor ratio, $\mu^{p} G^{p}_{E}/G^{p}_{M}$, have yielded dramatically different results using polarized and unpolarized techniques. The leading explanation for this discrepancy is the contribution of the hard two-photon exchange corrections. A proposed experiment at DESY aims to measure this contribution by measuring the ratio of positron-proton to electron-proton elastic scattering at lepton energies of 2 and 3 GeV. This talk will focus on test beams conducted in Fall 2019 and Fall 2021 at the DESY II synchrotron, which tested the performance of the PbWO$_{4}$ calorimeters, as well as triggered and streaming readout data acquisition systems. |
Sunday, April 10, 2022 4:33PM - 4:45PM |
L07.00004: Measurements of proton's electric and magnetic generalized polarizabilities Nikos Sparveris, Hamza Atac, Ruonan Li The Generalized Polarizabilities (GPs) are fundamental properties of the nucleon. They characterize the nucleon's response to an applied electromagnetic field, giving access to the polarization densities inside the nucleon. As such, they represent a central path towards a complete understanding of the nucleon dynamics. Previous measurements have challenged the theoretical predictions, raising questions in regard to the underlying mechanism responsible for a local enhancement of the electric GP at intermediate four-momentum transfer squared. The measurement of the magnetic GP, on the other hand, promises to quantify the interplay of the paramagnetic and the diamagnetic contributions inside the proton. New results on the proton GPs from the VCS experiment in Hall C at JLab will be presented in this talk. |
Sunday, April 10, 2022 4:45PM - 4:57PM |
L07.00005: Big data paradox in the global QCD analysis of proton structure Pavel M Nadolsky, Aurore Courtoy The big data paradox formulated by Xiao-Li Meng states that the more the data, the surer we fool ourselves. Precision physics programs at the high-luminosity Large Hadron Collider and Electron Ion Collider rely on large data sets to obtain tight constraints on parton distribution functions (PDFs) used for a variety of theoretical predictions. In the context of these programs, the big data paradox suggests that more experimental data do not automatically raise the accuracy of PDFs -- close attention to the data quality is as essential. On the example of the recent global analyses of proton PDFs by the CTEQ-TEA and other groups, we discuss how these issues affect PDF uncertainties in the key LHC processes. |
Sunday, April 10, 2022 4:57PM - 5:09PM |
L07.00006: Transverse momentum integrals and the positivity violations of collinear pdfs Ted C Rogers, Nobuo Sato, John C Collins I will summarize a collection of recent work related to the ultraviolet divergences that arise in collinear correlation functions from integrations over all transverse momentum. In particular, I will discuss the question of whether positivity of collinear pdfs is automatically guaranteed in particular renormalization schemes. |
Sunday, April 10, 2022 5:09PM - 5:21PM |
L07.00007: Precise Measurement of Charged Pion Cross-section and Ratios from Deuterium Hem D Bhatt The main goal of the experiment E12-09-002 is to measure the precise ratio of charged pion electroproduction ($\pi+$/$\pi-$) from deuterium in order to place constraints on the degree of charge symmetry violation (CSV) in the valence quark distributions in the nucleon via semi-inclusive deep inelastic scattering (SIDIS). The experiment was completed at Jefferson Lab HallC in spring 2019 with a 10.6 GeV electron beam on a liquid deuterium target. The scattered electrons and charged pions were detected in coincidence in two spectrometers, the HMS and SHMS respectively. The data were taken with x ranging from 0.35 to 0.65, z ranging from 0.4 to 0.7, and $Q^{2}$ ranging from 4 to 5.5 $GeV^{2}$. In this talk, I will be presenting preliminary $\pi+$ and $\pi-$ SIDIS cross-sections and their ratios. These results will be compared with current models and parametrizations. |
Sunday, April 10, 2022 5:21PM - 5:33PM Withdrawn |
L07.00008: Understanding the proton spin from lattice QCD Jack Holligan The aim is to understand the spin structure of the proton using lattice field theory techniques as well as large-momentum effective theory (LaMET). Only about 30% of the proton’s total spin comes from its valence-quarks. We wish to measure the spin-content of the sea-quarks and gluons (known collectively as partons) using the methods of lattice quantum chromodynamics (QCD). |
Sunday, April 10, 2022 5:33PM - 5:45PM |
L07.00009: Factorization, evolution and inverse matching of the quasi-PDF Yong Zhao In this talk, we discuss the factorization formula of the quasi-PDF in the large-momentum effective theory (LaMET). We show that by employing the momentum evolution equation of the quasi-PDF, we can derive the inverse matching formula that allows one to directly calculate the PDF from the quasi-PDF in the x-space. By deriving the next-to-next-to-leading order matching coefficient for the recently proposed hybrid scheme, we implement this inverse matching on a lattice QCD calculation of the pion valence quark PDF. The results show nice perturbative convergence and scale-uncertainty reduction, which is a promising step towards improving the precision of such calculations. |
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