Bulletin of the American Physical Society
87th annual meeting of the Southeastern Section of the APS
Volume 65, Number 19
Thursday–Friday, November 5–6, 2020; Virtual
Session F02: Medium Energy Nuclear Physics 2 |
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Chair: Lamiaa El-Fassi, Mississippi State University |
Friday, November 6, 2020 11:00AM - 11:12AM |
F02.00001: A Program of Spin-dependent Electron scattering from a Polarized $^3$He target in CLAS12 Dien Nguyen, Richard Milner, Harut Avakian, James Maxell We will present a new approved proposal using polarized $^3$He target and CLAS12 detector in Hall B at the JLab. This experiment will carry out a precision measurement of spin-dependent inclusive and semi-inclusive DIS (SIDIS) directly from a longitudinally polarized neutron over a large kinematic range: $0.05 < x < 0.7$, $1 < Q^{2} < 9$ (GeV/c)$^2$, $0.2 < z< 0.9$ and $0 < P_{T} < 1.3$ GeV/c. The principal scientific aim of this proposal is to extract the flavor dependence of the quark polarization and, in particular, determining their transverse momentum dependence. This experiment will also provide the data to study the nuclear correction to SIDIS in polarized $^3$He, compare them to those for the deuteron and confront the current theoretical understanding of the hadronization process in light nuclei. [Preview Abstract] |
Friday, November 6, 2020 11:12AM - 11:24AM |
F02.00002: Probing the neutron structure via polarized $^{3}$He with double-tagging at EIC Ivica Friscic, Dien Thi Nguyen, Jackson Reeves Pybus In several electron scattering experiments, polarized $^{3}$He plays a role of an effective polarized neutron target and enable us to study the spin-dependent structure of a neutron. With simultaneous detection of two spectator protons (double-tagging) it is possible to perform the spin-dependence study with minimization of nuclear effects. Here we present a study of the electron scattering from polarized $^{3}$He with double tagging at future Electron-Ion Collider (EIC) at two representative kinematics in terms of energies of colliding electron and ion beams with focus on two different regimes of $^3$He breakup: short-range correlations (SRC) and 3-body-breakup in the mean field (3BBU-MF). [Preview Abstract] |
Friday, November 6, 2020 11:24AM - 11:36AM |
F02.00003: Beam Asymmetry t-dependence for photoproduced $\eta\prime$ at GlueX Churamani Paudel, Joerg Reinhold The GlueX experiment is a photoproduction experiment which is located at Thomas Jefferson National Lab in Newport News, Virginia. We report on measurements of the beam asymmetry ($\Sigma$) in the reaction $\gamma p\rightarrow \eta' p$, using a tagged, linearly polarized 9 GeV photon beam incident on a liquid hydrogen target. A previous measurement, which was limited to momentum transfer up to $-$t=0.9 (GeV/c)$^2$, indicated that the reaction mechanism is dominated by $\rho$ and $\omega$ meson exchanges [1]. Newly collected data with 3-4 times larger statistics will allow us to study whether this holds true at larger momentum transfer. We will present the preliminary results of the ongoing analysis for azimuthal angular distributions, yield asymmetries and extracted beam asymmetries as a function of $-$t for different $\eta'$ decay modes. [Preview Abstract] |
Friday, November 6, 2020 11:36AM - 11:48AM |
F02.00004: Measurement of the $t$-dependence for the Beam Asymmetry of Photoproduced $\eta$ Mesons at GlueX Tolga Erbora, Joerg Reinhold We report on the photoproduction of $\eta$ mesons studied at the GlueX experiment at Thomas Jefferson National Laboratory in Newport News, VA. These particles are produced by a linearly polarized photon beam at energies between 8.2 and 8.8 GeV incident on protons in a liquid hydrogen target. Azimuthal ($\phi$) angular distributions with respect to the direction of the polarized photon facilitate the extraction of the beam asymmetry $\Sigma$ for the reaction $\vec\gamma p \rightarrow \eta p $. $\Sigma$ is derived as a function of four-momentum transfer $-t$. Compared with previous GlueX results [1,2,3], the 2018 run period produced approximately 3-4 times more statistics, thereby allowing us to extend these measurements to values beyond the previous limitation of $-t \leq$ 1.1 (GeV/$c$)$^2$. Preliminary results will be shown for events reconstructed from the decays of $\eta \rightarrow \pi^{+} \pi^{-} \pi^{0} $ and $\eta \rightarrow \gamma \gamma $. [1] S.~Adhikari {\it et al.} [GlueX Collaboration], Phys.\ Rev.\ C {\bf 100}, no. 5, 052201 (2019) [2] H.~Al Ghoul \textit{et al.} [GlueX],Phys. Rev. C \textbf{95}, no.4, 042201 (2017) [3] P.~Collins {\it et al.} [CLAS Collaboration], Phys.\ Lett.\ B {\bf 771}, 213 (2017) [Preview Abstract] |
Friday, November 6, 2020 11:48AM - 12:00PM |
F02.00005: Electroproduction of a Scalar $(0^{++})$ Meson off the Scalar Target Andrew Lundeen, Chueng-Ryong Ji We discuss the electroproduction of a scalar ($0^{++}$) meson off the scalar target. The most general formulation of the differential cross section for the $0^{++}$ meson production process involves only two hadronic form factors, respectively, on a scalar target. The Rosenbluth-type separation of the differential cross section provides an explicit relation between the hadronic form factors and the different parts of the differential cross section in a completely model-independent manner. The absence of the beam spin asymmetry for the pseudoscalar meson production provides a benchmark for the experimental data analysis as confirmed in the $\pi^0$ electroproduction off the $^4\text{He}$ target. Finally, we discuss a simple model calculation for finding the imaginary part of the hadronic amplitude, which can provide insight for measuring the non-vanishing beam spin asymmetry. [Preview Abstract] |
Friday, November 6, 2020 12:00PM - 12:12PM |
F02.00006: Search for the Onset of Color Transparency (CT) in Protons in Hall C at upgraded 12 GeV Jefferson Lab Deepak Bhetuwal CT is a unique prediction of QCD where the final (and/or initial) state interactions of hadrons with the nuclear medium are suppressed for exclusive processes at high momentum transfers. While this phenomenon has been observed for mesons, there has never been a conclusive observation for baryons. A clear signal of CT for baryons would be the first evidence of baryons fluctuating to a small size in the nucleus, and the onset would show the transition from partonic picture to quark-gluon degrees of freedom. The experiment E12-06-107 searching for the onset of CT in protons was completed in Hall C at Jefferson Lab using the recently upgraded 12 GeV e$^-$ beam. It used HMS and new SHMS spectrometers in coincidence to measure the $^{12}$C(e,e'p) proton knockout reaction. Data were collected on a $^{12}$C target over the range of Q$^2$ = 8 – 14.2 (GeV/c)$^2$ covering the region where a previous A(p,2p) experiment at BNL had observed an enhancement. Additional data on a $^1$H target were collected to determine the elementary process. A rise in the Proton Transparency (PT) as a function of Q$^2$ is predicted to be a signature of the onset of CT. This talk will summarize the status of the analysis, detail the systematic uncertainties calculation, and present the preliminary results. [Preview Abstract] |
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