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 KI: Mini-Symposium: Nucleon Structure and Interactions II |
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Chair: Burcu Duran, University of Tennessee Room: Hyatt Regency Hotel Imperial 12 |
Saturday, October 29, 2022 10:30AM - 10:42AM |
KI.00001: Nucleon Quark and Gluon Parton Distributions from Lattice QCD in the Continuum Limit Huey-Wen Lin We present the $x$-dependent nucleon quark and gluon parton distributions from lattice QCD on ensembles of $2+1+1$ flavors of highly improved staggered quarks (HISQ), generated by MILC Collaboration. We use three lattice spacings $a\approx 0.9, 0.12$ and 0.15~fm and multiple pion masses. We extrapolate our results to physical pion mass and the continuum limit, and compare our results with global fits. |
Saturday, October 29, 2022 10:42AM - 10:54AM |
KI.00002: Probing the isospin structure of short-range correlations using ρ0 meson photoproduction Phoebe Sharp Short Range Correlations (SRCs) are a feature of the internal structure of all types of nuclei. Characterized by high relative momentum and low center of mass momentum, SRC pairs have been well studied with quasi-elastic electron scattering experiments. The reliance on electron scattering however, makes it difficult to assess the influence of reaction effects and final state interactions on what has been learned so far about SRCs. For that reason, the Hall D Short Range Correlations Experiment was conducted at Jefferson Lab in Fall, 2021 using a real photon beam incident on nuclear targets to explore SRCs through various photoproduction channels, providing insight into different kinematic regions and different final states. Our preliminary analysis shows that the predictions of Generalized Contact Formalism (GCF) work well for photoproduction. In my analysis, I have considered ρ0 meson photoproduction from protons participating in SRCs as a tool for testing the correlations’ isospin structure, in order to verify the predominance of np-pairing observed in electron scattering. Preliminary results of testing np-pair dominance along with comparisons to GCF will be presented in this talk. |
Saturday, October 29, 2022 10:54AM - 11:06AM |
KI.00003: Measuring universality in nuclear short-range correlation interactions using ρ- photoproduction Jackson R Pybus Nuclear Short Range Correlations (SRCs) are pairs of nucleons which exist at short relative distance and high relative momentum within the nucleus. These SRC pairs have significant impacts on nuclear structure and have been extensively studied using quasi-elastic electron-scattering data. The phenomenological Generalized Contact Formalism (GCF) has been used in recent years to connect these measurements with the ground-state properties of nuclear SRCs, using a factorized, ground-state model to predict the cross sections and event yields for these data. These interpretations rely heavily on our understanding of the electron-scattering reaction mechanisms, limiting our ability to draw conclusions about the underlying properties of SRCs. In fall of 2021, our collaboration took data in Hall D of Jefferson Lab, using a real photon beam incident on nuclear targets to independently measure the properties of nuclear SRCs. Here we present the first observation of SRC signal events in this data using quasi-elastic ρ- meson photoproduction from correlated neutrons in deuterium, helium, and carbon nuclei, along with comparisons to the GCF predictions. We use the GCF to show consistency between the electron- and photo-scattering measurements; in this, we provide evidence for the universality of SRC properties across reactions, showing that several different hard reactions proceeding on correlated nucleons may be consistently explained using a single model. |
Saturday, October 29, 2022 11:06AM - 11:18AM |
KI.00004: Recent and Upcoming Inclusive Short Range Correlation Measurements in Hall C at Jefferson Lab Casey A Morean, Nadia Fomin Short range correlations (SRCs) are a major component of the high-momentum tail in nuclei. SRCs give us a wealth of knowledge on the high momentum and short-range component of the nucleon-nucleon (NN) interaction. A linear correlation between SRC pairs and the EMC effect became evident from the 6 GeV experiments in Hall C at JLab. Additional measurements of both EMC effect and SRCs for a large set of light nuclei will give new information on the correlation seen in the previous 6 GeV experiment. As a part of commissioning of the super high momentum spectrometer, several light nuclear targets were studied for the first time; boron-10 and boron-11. Commissioning results from boron-10 and boron-11 will be presented along with an update on the full experiment running currently at Jefferson Lab. |
Saturday, October 29, 2022 11:18AM - 11:30AM |
KI.00005: Measurement of the Neutron Electromagnetic Form Factor at High Q2 and GEM Detector Performance Sean Jeffas The neutron electromagnetic form factors, GEn and GMn, give important insights into the neutron structure. In previous experiments the proton electromagnetic form factors, GEp, was measured up to Q2 = 8.5 GeV2, and GMp was measured up to Q2 = 30 GeV2, while GEn has only been measured up to Q2 = 3.4 GeV2. The Super BigBite Spectrometer (SBS) program at JLab will measure the neutron form factor ratio, GEn/GMn, at Q2 values of 1.5, 3.8, 6.8, and 10.2 GeV2 by colliding a polarized electron beam with a polarized 3He target, used here as an effective polarized neutron target, and measuring the transverse asymmetry of the cross section. Scattered electrons are measured in the BigBite spectrometer equipped with Gas Electron Multiplier (GEM) detector based tracker, while scattered neutrons are magnetically separated from scattered protons and detected in a segmented hadron calorimeter. GEM tracking detectors measure the scattered electrons trajectory with 70 μm resolution and can operate at rates up to 500 kH/cm2. A new high voltage design was implemented prior to this experiment to improve the GEM efficiency and preliminary performace will be presented. |
Saturday, October 29, 2022 11:30AM - 11:42AM |
KI.00006: Testing the EMC-SRC Hypothesis with the BAND Experiment Sara Ratliff The EMC effect, the observation that Deep Inelastic Scattering (DIS) from bound nucleons differs significantly from that on free nucleons, has puzzled nuclear physicists for nearly forty years. A potential cause for this phenomenon is the formation of short-range correlations (SRCs) between nucleons within a nucleus, which can lead to significant changes in partonic structure. This hypothesis can be directly tested using the technique of recoil-tagging, in which the detection of the correlated spectator nucleon can reveal that the struck nucleon was part of an SRC. The Backward Angle Neutron Detector (BAND) was designed to tag recoiling neutrons in DIS on protons bound in deuterium. BAND was installed as part of the CLAS12 spectrometer in Hall B of Jefferson Lab and took production data in 2019-2020. This talk will discuss the current status of the BAND analysis, whose results will further our understanding of the relationship between the EMC Effect and short-range correlations in nuclei. |
Saturday, October 29, 2022 11:42AM - 11:54AM |
KI.00007: Preliminary results of Short-Range Correlations study in exotic nuclei at R3B. Hang Qi Short Range Correlations (SRC) are pairs of strong interacting nucleons with high relative momentum and low center of mass momentum compared to the Fermi momentum. The R3B S522 experiment run in 2022 at GSI, Germany and studied SRCs in the 12C and 16C isotopes, via the scattering of high energy ion beams off proton target in inverse kinematics. Using an exclusive measurement, we study for the first time SRC properties in exotic short lived nuclei, including their pair ratio and momentum distributions, paving the way for studying SRC physics in a neutron-rich environment. In this talk I will overview the experiment, discuss the calibration of several detectors and present the preliminary analysis results. |
Saturday, October 29, 2022 11:54AM - 12:06PM |
KI.00008: Extraction of the Sivers function from SIDIS, Drell-Yan, and W±/Z boson production Alexei Prokudin, Alexey Vladimirov, Marcin Bury We perform a global fit of the available polarized Semi-Inclusive Deep Inelastic Scattering (SIDIS), polarized pion-induced Drell-Yan (DY) and W±/Z boson production data at N3LO and NNLO accuracy of the Transverse Momentum Dependent (TMD) evolution, and extract the Sivers function for u, d, s and for sea quarks. The Qiu-Sterman function is determined in a model independent way via the operator product expansion from the extracted Sivers function. The analysis is supplemented by additional studies, such as the estimation of applicability region, the impact of the unpolarized distributions' uncertainties, the universality of the Sivers functions, positivity constraints, the significance of the sign-change relation, and the comparison with the existing extractions. |
Saturday, October 29, 2022 12:06PM - 12:18PM |
KI.00009: Measurements of the Cosφ and Cos2φ Moments of the Unpolarized SIDIS π+ Cross-section at CLAS12 Richard A Capobianco Semi-inclusive deep inelastic π+ electroproduction has been studied with the CLAS12 detector at Jefferson Laboratory. Data was taken with a polarized 10.6 GeV electron beam, interacting with an unpolarized liquid hydrogen target. The collected statistics enable a high-precision study of the Cosφ and Cos2φ azimuthal moments of the unpolarized cross-sections. These azimuthal moments may probe the Boer-Mulders function, which describes the net polarization of quarks inside an unpolarized proton, and the Cahn effect, which has a purely kinematic origin. The high statistics data will, for the first time, enable a multidimensional analysis of both moments over a large kinematic range of Q2, xB, z, and pT. We will present the status of this ongoing analysis, including the acceptance corrections. |
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