Bulletin of the American Physical Society
2021 Fall Meeting of the APS Division of Nuclear Physics
Volume 66, Number 8
Monday–Thursday, October 11–14, 2021; Virtual; Eastern Daylight Time
Session EC: 1D Parton Structure of Hadrons II |
Hide Abstracts |
Chair: Jae Nam, Temple University Room: Studio 2 |
Tuesday, October 12, 2021 11:45AM - 11:57AM |
EC.00001: Measurements of longitudinal double-spin asymmetries of inclusive jet and dijet production at STAR Amilkar A Quintero In 2015, the STAR experiment concluded the collection of longitudinally polarized proton-proton collision data, mainly dedicated to study the gluon helicity distribution function (∆g(x)) of the proton. This function can be accessed by measuring the longitudinal double-spin asymmetry (ALL) of inclusive jet and dijet production in proton-proton collisions. Measurements at √s = 200 GeV and 510 GeV were taken to maximize the kinematic coverage in momentum fraction (x) down to x ~ 0.01. The wide acceptance of the STAR experiment permits the reconstruction of jets with different topological configurations to better constrain the shape of the gluon helicity function. In this talk, we present the results of STAR ALL measurements in proton-proton collisions at √s = 200 GeV and 510 GeV, at mid-pseudorapidity (|η|<1) and intermediate-pseudorapidity (-0.8<η<1.8). These results are compared with the latest QCD global analyses. |
Tuesday, October 12, 2021 11:57AM - 12:09PM |
EC.00002: Constraining gluon helicity distributions in proton Yiyu Zhou, Nobuo Sato, Wally Melnitchouk We made simultaneous extraction of spin averaged and spin dependent PDFs within multistep MC procedures, with combined analysis of inclusive unpolarized and polarized jets from RHIC to Tevatron energies. By analyzing the preliminary results we had, we were able to discuss impact of theory assumptions on $\Delta g$. |
Tuesday, October 12, 2021 12:09PM - 12:21PM |
EC.00003: Probing Charge Symmetry Violation in Quark Distributions using SIDIS Hem D Bhatt Charge symmetry is generally assumed to be valid in global fits of data to extract parton distribution functions. At the quark level, the violation of this symmetry arises due to the small mass difference between the up and the down quarks as well as the electromagnetic interaction between the quarks. Although the charge symmetry violation (CSV) is expected to be very small, the precision of the existing data can only constrain it to be $\ < ± 10 \%$. Jefferson Lab Hall-C experiment E12-09-002 was the first experiment that aimed to place constraints on the degree of CSV in the valence quark distributions in the nucleon via semi-inclusive deep inelastic scattering (SIDIS). In this experiment, a 10.6 GeV electron beam was incident on a liquid deuterium target with the scattered electrons and charged pions detected in coincidence in the HMS and SHMS spectrometers respectively. We measure the ratios of charged pion cross-sections with high precision to extract and place limits on the charge symmetry violating parton distribution functions. In this talk, we will discuss some preliminary cross-section ratios of charged pions, preliminary results on factorization tests, and compare them to the results from the 6 GeV era. |
Tuesday, October 12, 2021 12:21PM - 12:33PM |
EC.00004: Global QCD Analysis of Pion Parton Distributions Using Threshold Resummation Patrick C Barry, Chueng-Ryong Ji, Nobuo Sato, Wally Melnitchouk We perform the first global QCD analysis on pion valence quark, sea quark, and gluon distributions including threshold resummation on Drell-Yan cross sections within a Bayesian Monte Carlo framework. Various methods of threshold resummation stemming from treatment of the rapidity distribution are applied systematically on the pion-nucleus Drell-Yan observables. We present the results of the large momentum fraction behavior of the valence quark distribution, which differs significantly depending on the method of resummation. In contrast, the momentum fractions of the various distributions are equal within uncertainties regardless of the resummation method. |
Tuesday, October 12, 2021 12:33PM - 12:45PM |
EC.00005: Studies of Meson Structure at the EIC Richard L Trotta The space and momentum distribution of hadronic constituents (gluons, sea quarks) inside the nucleon is of utmost importance in studies of QCD. Deeper considerations of the lightest mesons (pions, kaons) could provide insights into many questions that plague modern QCD studies. The Electron-Ion Collider (EIC) will provide access to a large kinematic range in the longitudinal momentum fraction, x, and the four-momentum transfer, Q2. These would allow the extraction of structure functions and the pion and kaon form factors which would allow one to probe the differences of gluon content in pions, kaons, and nucleons. While the EIC is under development, Monte Carlo simulations are a quick and effective approach for feasibility studies of the meson structure measurements in the high x region. The EIC will have the capacity to host two interaction regions, each with a corresponding detector. Meson structure function studies are the main driver for far-forward region design. Optimization of the first beamline was done for the EIC YR while the second beamline is currently undergoing a more detailed design. I will be discussing the optimization of these beamlines and contributions to the PDF global fitting community. |
Tuesday, October 12, 2021 12:45PM - 12:57PM |
EC.00006: Jefferson Lab Hall A High Luminosity Spectator Tagged Physics program Salina F Ali Jefferson Lab Hall A spectator tagged physics program will allow precision measurements of high luminosity electron scattering off effectively free pion, kaon and neutron targets. This will make possible the measurement of some of the most sought after quantities in particle physics such as a direct, precision measurement of the elusive meson content of the nucleon, structure functions of pions and kaons, and Deeply Virtual Compton Scattering (DVCS) on the neutron. This program is centered around a multi-Time Projection Chamber (mTPC) optimized to detect low-momentum particle tracks in extreme high background rate conditions. The upcoming Tagged Deep Inelastic Scattering (TDIS) experiment will measure semi-inclusive eN → e'N'X reactions in the deep inelastic regime through the spectator tagging technique, or the Sullivan process. The experiment will invoke the Sullivan process by tagging low-momentum recoiling and spectator protons with the mTPC device in conjunction with the scattered electron detected by the Super Bigbite Spectrometer (SBS). The data would provide access to pion and kaon structure functions in a new kinematical domain, allowing a probe of the mesonic structure of the nucleon. In this talk, I will present the current status of the TDIS experiment and prospects of the spectator tagged physics program. |
Tuesday, October 12, 2021 12:57PM - 1:09PM |
EC.00007: Exploring Free and Bound Nucleon Structure Using Tagged DIS Measurements at the EIC Alexander M Jentsch, Zhoudunming Tu, Christian Weiss Measurements of DIS on the deuteron where the spectator nucleon is tagged in the final state (spectator tagging) enable access to both free nucleon structure, and nuclear modifications of bound nucleons. The use of the deuteron also enables access to an effective neutron beam in a collider, which allows for removal of nuclear binding effects present at very low transverse momentum ($<$ 100 MeV/c) via use of pole extrapolation – an improvement over currently available fixed-target measurements with light nuclear targets. The detection of the spectator nucleon fixes the nuclear configuration during the DIS process and permits differential studies of the nuclear modifications. In electron + deuteron measurements at the EIC the spectator nucleon is scattered at $\eta > 4.5$ - so called ``far-forward" rapidities. We present here detailed comparisons of the method of pole extrapolation for extraction of free nucleon structure with inclusive measurements using the BeAGLE event generator for e+d DIS events, as well as preliminary results and outlook for the study of nuclear modifications. We also present results on the feasibility of tagged DIS measurements with the baseline EIC far-forward detector design using realistic detector simulations for both proton and neutron detection. |
Tuesday, October 12, 2021 1:09PM - 1:21PM |
EC.00008: A Multithreaded Tracking Algorithm for E1039/SpinQuest Noah B Wuerfel The SpinQuest (Fermilab E1039) experiment will measure an azimuthal asymmetry in the Drell-Yan production of $\mu+$ $\mu-$ pairs from 120 GeV/c proton interactions with polarized nucleons to extract the Sivers function for $\bar{u}$ and $\bar{d}$. A nonzero asymmetry would be "smoking gun" evidence for orbital angular momentum of the light sea-quarks: a possible contributor to the proton's spin. Reconstructing the primary physics event requires precision tracking of the dimuon pair against a combinatorial background of single muons produced in the beam dump. Raw data from the DAQ must be decoded and tracked in the 55 seconds between beam spills of the Fermilab main injector to provide online monitoring. Sequential tracking of events is too slow, but the prevalence of affordable, multi-CPU hardware makes a parallel solution an attractive possibility. In this talk, I will discuss updates to the development and performance of a multithreaded tracking algorithm, using ROOT tools, capable of parallel event tracking for the SpinQuest online monitoring system. |
Tuesday, October 12, 2021 1:21PM - 1:33PM |
EC.00009: Proton structure functions in the resonance region Astrid N Hiller Blin, Victor I Mokeev, Adam P Szczepaniak, Volker D Burkert, Alessandro Pilloni, Wally Melnitchouk, Vitaly V Chesnokov Nucleon resonance contributions to the inclusive proton F2 and FL structure functions are computed from resonance electroexcitation amplitudes in the mass range up to 1.75 GeV extracted from CLAS exclusive meson electroproduction data. Taking into account for the first time interference effects between nucleon resonances, the resonant contributions are compared with inclusive proton structure functions evaluated from cross section data and the longitudinal to transverse cross section ratio. Contributions from isospin-1/2 and 3/2 resonances remain substantial over the entire range of photon virtualities < 4 GeV^2 , where their electroexcitation amplitudes have been obtained, and their Q^2 evolution displays pronounced differences in the first, second and third resonance regions. We compare the structure functions in the resonance region with those computed from parton distributions fitted to deep-inelastic scattering data, and extrapolated to the resonance region, providing new quantitative assessments of quark-hadron duality in inclusive electron-proton scattering. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700