Bulletin of the American Physical Society
88th Annual Meeting of the Southeastern Section of the APS
Volume 66, Number 16
Thursday–Saturday, November 18–20, 2021; University Center Club, Florida State University, Tallahassee, Florida
Session M01: Medium and High Energy Physics II |
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Chair: Sean Dobbs, Florida State University Room: East Ballroom |
Friday, November 19, 2021 2:00PM - 2:30PM |
M01.00001: Hypernuclear Spectroscopy at Jefferson Lab Invited Speaker: Joerg Reinhold The central question of nuclear science is the structure of nuclear matter. For a complete understanding of the evolution of nuclear matter in the universe, detailed knowledge is necessary not only for stable nuclei, but also increasingly for unstable and exotic nuclear matter. Nuclear matter containing strangeness is thought to play an important role in stellar objects like neutron stars. The knowledge of the underlying interaction between strange baryons (hyperons) and nucleons (protons and neutrons) is incomplete. A complete theory of baryon-baryon interactions in the context of the underlying QCD degrees of freedom, quarks and gluons, will ultimately also have to describe interactions with and between strange baryons. In the laboratory, these can be best studied by implanting hyperons in ordinary nuclei, thus converting them to hypernuclei. The high quality electron beam at Jefferson Lab allowed for the first time to study hypernuclei by (e,e'K$^+$) reaction spectroscopy. Six experiments on a number of light to medium heavy targets were conducted. Currently, the hypernuclear spectroscopy system at Jefferson Lab is being upgraded to ensure compatibility with the higher beam energies after the 12 GeV upgrade. Four new experiments have already been approved. They will measure the hyperhydrogen nuclei $^3_\Lambda$H and $^4_\Lambda$H; comparison to $^3_\Lambda$He and $^4_\Lambda$He addresses charge symmetry breaking or isospin dependence. Spectroscopy of $^{40}_\Lambda$K and $^{48}_\Lambda$K will study the isospin dependence of the 3-body $\Lambda$nn force. Finally, a study of the $^{208}$Pb(e,e'K$^+$)$^{208}_\Lambda$Tl reaction will provide data on an extended nucleus with large neutron excess; this is the closest approximation to neutron star matter than can be achieved in the laboratory. In this talk, I will first introduce the topic of hypernuclear physics and then review the results from the previous program. I will conclude with an outlook on the future experiments. [Preview Abstract] |
Friday, November 19, 2021 2:30PM - 3:00PM |
M01.00002: Grounding nuclear physics in the strong nuclear force Invited Speaker: Christopher Monahan Predicting the properties of nucleons and nuclei directly from the interactions of quarks and gluons, governed by quantum chromodynamics (QCD), is a long-standing challenge for nuclear physics. At the energies relevant to nuclear physics, QCD is strongly coupled and cannot be solved analytically. The solution to this is lattice QCD, in which the strong nuclear force is formulated in a discretised finite box (the "lattice") and correlation functions are determined stochastically. I will review recent progress in understanding nucleons and light nuclei directly from lattice QCD calculations and highlight some key contributions to our theoretical understanding of nuclear physics. [Preview Abstract] |
Friday, November 19, 2021 3:00PM - 3:15PM |
M01.00003: $\Xi(1320)^-$ Differential Cross Section in Photoproduction at GlueX Jesse Hernandez For decades an assortment of quark models and more recently lattice QCD calculations have predicted many more baryon states than have been experimentally observed. Furthermore, the fundamental physics of flavor SU(3) symmetry indicates that there should be a Cascade partner for every $N^*$- and $\Delta ^*$- resonance observed. The doubly strange baryon, i.e., $\Xi$, in particular, overwhelmingly lacks these states experimentally. The GlueX experiment at Hall D in Jefferson Lab has accumulated high statistics data of photoproduction. Using this high statistics data and the fact that the lowest lying Cascade states have very narrow peaks we will be able to study the systematics of the spectrum in detail. In addition, we will study the production mechanism that produces these Cascade resonance, which, has not been studied extensively. We will report the differential cross section for $\Xi(1320)^-$ in the exclusive t-channel production reaction $\gamma p \rightarrow K^+ Y^* \rightarrow K^+(K^+\Xi^-)$ where $\Xi^-\rightarrow \Lambda \pi^-$. With this measurement we will get a better understanding of the production mechanism, i.e., $Y^*$ states, in photoproduction. [Preview Abstract] |
Friday, November 19, 2021 3:15PM - 3:30PM |
M01.00004: Lambda\textasciicircum 0 Asymmetry at Belle II Matthew Mestayer, Jake Bennett This analysis uses data and simulations from the Belle II experiment at the SuperKEKB electron-positron collider in Tsukuba, Japan to study the detection asymmetry of Lambda\textasciicircum 0 decaying to a proton and a pion. These results will be helpful to validate the detector and are necessary input for studies of CP asymmetries in charmed baryon decays. [Preview Abstract] |
Friday, November 19, 2021 3:30PM - 3:45PM |
M01.00005: 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. A linearly polarized photon beam at energies between 8.2 and 8.8 GeV, incident on a liquid hydrogen target, produces $\eta$ dominantly through $t$-channel exchanges. Azimuthal angular distributions of the $\eta$, with respect to the direction of the polarized photon facilitate the extraction of the beam asymmetry $\Sigma$ for the reaction $\vec\gamma p \rightarrow \eta p$. We can understand the production mechanisms of the $\eta$ by analyzing $\Sigma_\eta$, which is sensitive to the particles exchanged. Compared to previous GlueX results [1,2], we have access to six times the 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 decay of $\eta \rightarrow \gamma \gamma$. [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 Collaboration], Phys. Rev. C \textbf{95}, no. 4, 042201 (2017) [Preview Abstract] |
Friday, November 19, 2021 3:45PM - 4:00PM |
M01.00006: Study of the Reaction \(\gamma p \rightarrow \eta \eta' p\) Jason Barlow The motivation behind the GlueX experiment is to search for hybrid mesons. There is strong evidence for the exotic \(\pi_{1}(1600)\) which has been observed in \(\eta'\pi\). The \(\pi_{1}(1600)\) has an isoscalar partner, the \(\eta_{1}\), which can possibly be observed in the \(\eta'\eta\) channel. The preliminary analysis presented here considers photoproduction of the final state \(\eta'\eta\) which decays to 4\(\gamma\pi^{+}\pi^{-}\). The experiment uses a beam of linearly polarized photons with a peak near 9 GeV incident on a hydrogen target that produces these particles. General features of the data including data selection with a focus on removing backgrounds due to wrong photon combinations will be shown. Mass spectra and intermediate states will be also be presented. [Preview Abstract] |
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