Bulletin of the American Physical Society
APS April Meeting 2022
Volume 67, Number 6
Saturday–Tuesday, April 9–12, 2022; New York
Session H11: Mini-symposium: Multidimensional Structure of Hadrons IIMini-Symposium Recordings Available
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Sponsoring Units: DNP Chair: Francois-Xavier Girod, Jefferson Lab/Jefferson Science Associates Room: Majestic |
Sunday, April 10, 2022 10:45AM - 10:57AM |
H11.00001: Comprehensive Study of SSAs within the JAM Global Analysis Framework Daniel Pitonyak, Leonard Gamberg, Michel J Malda, Joshua A Miller, Alexei Prokudin, Nobuo Sato The analysis of single transverse-spin asymmetries (SSAs) gives us tremendous insight into the internal structure of hadrons. For example, the Sivers and Collins effects in semi-inclusive deep-inelastic scattering (SIDIS), Sivers effect in Drell-Yan, and the Collins effect in electron-positron annihilation have been widely investigated over many years in order to perform 3D momentum-space tomography. In addition, observables like AN in proton-proton collisions are of interest due to their sensitivity to quark-gluon correlations. In this talk I will discuss an updated QCD global fit of SSA data, within the Jefferson Lab Angular Momentum (JAM) Collaboration framework, from SIDIS, Drell-Yan, e+e− annihilation into hadron pairs, and proton-proton collisions. This includes now the impact of new SIDIS and pion AN data on our analysis, jet AN data, Collins hadron-in-jet measurements, as well as the role of lattice data on the tensor charge and the Soffer bound on transversity, in an attempt to give a comprehensive study of our current understanding of transverse SSAs. |
Sunday, April 10, 2022 10:57AM - 11:09AM |
H11.00002: Di-hadron correlations in $e^-$A DIS with CLAS Sebouh J Paul We present a measurement of the nuclear dependence of di-hadron production in deep inelastic scattering off nuclei using the CLAS detector at Jefferson Lab. We report results on the di-hadron correlation functions (that is, the probability of detecting a second hadron given the detection of the first) for charged pions using deuterium, carbon, iron, and lead data. By making separate measurements for each target type, the results complement earlier measurements of nuclear-to-deuterium ratios for single- and/or di-hadron yields, and may help constrain models of interactions between hadrons and the nuclear medium. We report the first measurement of azimuthal and rapidity correlations in nuclear DIS, which shows a strong suppression for back-to-back pion pairs in nuclei, whereas we observe an enhancement for such pairs where the azimuthal and rapidity separations are both small. This represents a new type of study in electron-nucleus collisions and serves as a pathfinder for future experiments with CLAS12 and the Electron-Ion Collider. |
Sunday, April 10, 2022 11:09AM - 11:21AM |
H11.00003: Multi-Dimensional Studies of the ep->e’p’X reaction with CLAS12 at Jefferson Lab Fatiha Benmokhtar, Alyssa L Gadsby, Timothy Hayward, Harut Avagyan Studies of the properties and the azimuthal distribution of hadrons produced in the Target Fragmentation Region serve as a test of our complete understanding of the different mechanisms in the SIDIS production of hadrons and provide additional information on the QCD dynamics that are not accessible with single hadron production in the Current Fragmentation Region. We present first studies of beam SSA for semi-inclusive protons (ep → e′p'X), produced in the TFR, that can be related to higher twist Fracture Functions describing the FLU structure function. Such measurements on target-fragmentation protons were performed with the CLAS12 detector in Hall B at Jefferson lab. The preliminary results presented in this talk spanned the run period of fall 2018. |
Sunday, April 10, 2022 11:21AM - 11:33AM |
H11.00004: Online Reconstruction on GPUs for J/ψ TSSA Study at SpinQuest Catherine Ayuso The E1039/SpinQuest experiment is a transversely polarized fixed target experiment at Fermi National Accelerator Laboratory aiming to explore the sea quark and gluon Sivers functions via the measurement of the transverse single-spin asymmetry (TSSA) for a number of physics processes including J/ψ, ψ' and Drell-Yan production. The experiment employs a 120-GeV extracted proton beam colliding with transversely-polarized NH3 and ND3 cryogenic targets and its spectrometer is optimized to detect the oppositely-charged muon pair output of these processes. In pursuit of these asymmetry measurements, we are developing an advanced graphics processing unit (GPU) based multi-threaded framework that allows for efficient parallelization of the online data processing flow and track reconstruction along with diagnostics and visualization tools. In this talk, I will report performance metrics and the status of optimization of the offline track reconstruction software at SpinQuest on GPUs and discuss how we are implementing and reaching successful real-time data visualization and monitoring in preparation for SpinQuest's first production run in 2022. Moreover, I will present results estimating the anticipated precision of a TSSA measurement via the J/ψ process from the first SpinQuest production data as well as its associated efficiency studies. |
Sunday, April 10, 2022 11:33AM - 11:45AM |
H11.00005: Probing transverse-spin-dependent nucleon structure in pion-induced dimuon production at COMPASS April M Townsend COMPASS is a fixed target experiment in the North Area of CERN with a broad physics program. One of its primary goals is to study the Transverse Momentum Dependent (TMD) Parton Distribution Functions (PDFs) that describe the substructure of nucleons. In 2015 and 2018 COMPASS recorded Drell-Yan (DY) and J/ψ events produced in the collisions of a 190 GeV/c negative pion beam with a transversely polarized proton target. Transverse-spin-dependent azimuthal asymmetries (TSAs) in the dimuon angular distributions of these collisions can be used to test the predicted sign change of the quark Sivers TMD PDF when measured in DY compared to semi-inclusive deep inelastic scattering. In addition, TSAs in J/ψ production may give access to gluon TMD PDFs and improve our understanding of the J/ψ production mechanism. Results from the analysis of 2015 and 2018 COMPASS data will be presented. |
Sunday, April 10, 2022 11:45AM - 11:57AM |
H11.00006: Global Analysis of Worm-Gear TMD g1T Shohini Bhattacharya, Zhongbo Kang, Andreas Metz, Gregory D Penn, Daniel Pitonyak Transverse momentum dependent parton distributions (TMDs) are an important class of functions required to understand the 3D structure of hadrons in terms of their underlying partons. One of the least known TMDs in terms of a global QCD analysis is the worm-gear TMD g1T which represents the probablity of finding longitudinally polarized quarks inside transversely polarized hadrons. In this talk, we present the first-ever global QCD analysis of the semi-inclusive DIS ALT data using Monte Carlo techniques to extract the worm-gear TMD g1T. The relevant data are available from HERMES, COMPASS and JLab. We compare our results for g1T with different theoretical predictions, such as the large-Nc approximation, the Wandzura-Wilczek-type approximation, and lattice QCD. |
Sunday, April 10, 2022 11:57AM - 12:09PM |
H11.00007: Boer-Mulders Function at Small x M. Gabriel G Santiago, Yuri V Kovchegov We apply the formalism developed earlier by Kovchegov, Pitonyak, and Sievert for constructing transverse momentum dependent parton distribution functions (TMDs) at small Bjorken-x to derive the small-x evolution equations for the Boer-Mulders TMD. We construct evolution equations which resum double logarithms αs ln2(1/x), obtaining a closed set of equations in the large Nc limit. |
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