Bulletin of the American Physical Society
2020 Fall Meeting of the APS Division of Nuclear Physics
Volume 65, Number 12
Thursday–Sunday, October 29–November 1 2020; Time Zone: Central Time, USA
Session EH: Mini-Symposium: Hyper Nuclear Spectroscopy II |
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Chair: Toshiyuki Gogami, Kyoto University |
Friday, October 30, 2020 10:30AM - 10:42AM |
EH.00001: Isospin dependence study of potassium hypernuclei via the high-resolution mass spectroscopy at JLab. Sho Nagao, Satoshi Nakamura, Franco Garibaldi, Pete Markowitz, Joerg Reinhold, Liguang Tang, Guido Guido Investigation of the $\Lambda $N interaction in the nuclear medium is essential to describe a core structure of the neutron stars whose mass is around two solar mass. JLab E12-15-008 aims to measure the first experimental data about the $\Lambda $NN isospin dependent force via the (e,e'K$+)$ reaction spectroscopy of 40 and 48 potassium hypernuclear isotopes. We have constructed new magnets named Particle Charge Separator (PCS) to achieve the high mass resolution and the high hypernuclear yield simultaneously. Accuracy of Lambda binding energies is expected to be \textless 100 keV, that is enough energy to separate the isotope dependence of Potassium hypernuclei. I will introduce the physics motivation, expected results, and preparation status of the potassium hypernuclear experiment. [Preview Abstract] |
Friday, October 30, 2020 10:42AM - 10:54AM |
EH.00002: Inclusive measurement of strangeness photo-production and N$\Delta$ resonance state search on a deuterium target Yuichi Toyama, Masashi Kaneta, Sho Nagao, Satoshi N. Nakamura Photo-production of strangeness has been mainly studied by the reaction of charged channels ( e.g.: $\gamma+p\to K^{+} + \Lambda$). However, photo-production of $K^0$ meson through neutral channel ($\gamma+n \to K^0+\Lambda$) is not sufficiently studied due to experimental difficulties. The most reasonable way to study the reaction is to use a deuteron target as a quasi free neutron target since a lone neutron target is impractical. The cross section measurement would be good benchmark for isobar models. Thus, we have been investigated strangeness photo-production using a deuterium target with Neutral Kaon Spectrometer2 (NKS2) at the Research Center for Electron Photon Science (ELPH), Tohoku University, Japan. NKS2 is a magnetic spectrometer with a large solid angle (25\% of total) and multi charged particle detection capability. In the experiment, a few MHz tagged photon beam at energies ranging from 0.8 to 1.1 GeV was bombarded to the liquid deuterium target (520 mg/cm${}^{2}$). Mass of $K^0$ and $\Lambda$ were used as sources of momentum calibration of NKS2 in the analysis. In the presentation, I will report recent result about $N\Delta$ dibaryon candidate via the $\gamma + d \to d + \pi^{+} +\pi^{-}$ reaction, and the cross-section of $\Lambda$ and $K^0$ photo-production. [Preview Abstract] |
Friday, October 30, 2020 10:54AM - 11:06AM |
EH.00003: Studying $\Lambda $ interactions in nuclear matter with the $^{\mathrm{208}}_{\mathrm{\Lambda }}$Pb(e,e'K$^{\mathrm{+}})^{\mathrm{208}}_{\mathrm{\Lambda }}$Tl reaction Guido Maria Urciuoli, Omar Benhar, Petr Bydzovsky, Silviu Covrig Dusa, Franco Garibaldi, Toshiyuki Gogami, Pete Markowitz, John Millener, Satoshi Nakamura, Toshio Motoba, Joerg Reinhod, Liguang Tang, Vidana Isaac In view of astrophysical implications, a proposal of an experiment aiming at measuring $\Lambda $ binding energies of several energy levels of the hypernucleus $^{\mathrm{208}}_{\mathrm{\Lambda }}$Tl was submitted to JLab Program Advisory Committee. $^{\mathrm{208}}_{\mathrm{\Lambda }}$Tl hypernuclei will be produced through the $^{\mathrm{208}}_{\mathrm{\Lambda }}$Pb(e,e'K$^{\mathrm{+}})^{\mathrm{208}}_{\mathrm{\Lambda }}$Tl reaction. Thanks to the extended region of constant density and the large neutron excess, $^{\mathrm{208}}$Pb provides the best available proxy of neutron star matter. The experiment will provide essential information, needed to constrain and improve the available models of Hyperon-Nucleon and Hyperon-Nucleon-Nucleon potentials and therefore confirm whether hyperonic three-body forces could be the solution to the so-called hyperon-puzzle, the impossibility of reconciling the existence of very massive (up to two solar masses) neutron stars with the presence of hyperons in the interior of these objects. [Preview Abstract] |
Friday, October 30, 2020 11:06AM - 11:18AM |
EH.00004: Hyperon Spectroscopy with GlueX: $\Lambda(1520) \to \Sigma^{0}\gamma$ Nilanga Wickramaarachchi, Grzegorz Kalicy Radiative decay widths of hyperons are important inputs to extract information about the SU(3) structure of the wave functions of the hyperons. Measuring the wave function can discriminate between theoretical models of their structure. There have been only few measurements so far for the radiative decay of excited state hyperons. The branching fraction for $\Lambda(1520) \to \Sigma^{0}\gamma$ in particular has not been measured so far. The GlueX experiment at Jefferson Lab provides an excellent opportunity to study excited state hyperons in photoproduction with a photon beam in the energy range 3.0 - 11.6 GeV incident on a liquid hydrogen target. In this talk, we focus on the preliminary results from analyzing the reaction $\gamma p \to K^{+}\Lambda(1520)$ with $\Lambda(1520) \to \Sigma^{0}\gamma$ decay mode using the data collected during the first phase of the GlueX experiment. [Preview Abstract] |
Friday, October 30, 2020 11:18AM - 11:30AM |
EH.00005: Lambda Nucleon Scattering with the CLAS Detector Joseph Rowley, Ken Hicks Elastic $\Lambda p$ scattering might take place in the center of neutron stars. To better understand their equation of state, better data is needed for this reaction. Currently, data primarily comes from bubble chamber era experiments in part because of the difficulty of creating an exotic $\Lambda$ beam. Thus, $\Lambda N$ data is very limited compared to other elastic scattering processes, such as $NN$, $KN$ and $\pi N$. However, the richness of $\Lambda$ production in modern day accelerators has never been realized. Using the CLAS detector in Hall B of Jefferson Lab, data was mined from existing experiments from the g12 run. A high luminosity photon beam incident on a 40 cm liquid hydrogen target allows for a $\Lambda$ beam to be created inside the target. The cross sections presented are much more precise ($<$10\%) than previous measurements, which had statistical uncertainties between 20\%-50\% in the incident momentum range 1.0-1.6 GeV/c. Our results are compared with calculations based on effective field theory, along with predictions from the Nijmegan and Julich models. [Preview Abstract] |
Friday, October 30, 2020 11:30AM - 11:42AM |
EH.00006: Photoproduction of $\Lambda^*$ at CLAS Utsav Shrestha, Kenneth Hicks Much is known about the photoproduction of the hyperon resonances $\Lambda(1405)1/2^-$ and $\Lambda(1520)3/2^-$, but little is known about photoproduction to the higher-mass resonances $\Lambda(1670)1/2^-$ and $\Lambda(1690)3/2^-$. Both pairs of resonances are spin-orbit partners and are rated as 4-star (well-known) by the Particle Data Group. In the quark model, the $\Lambda(1405)$ and $\Lambda(1520)$ resonances are assigned to the SU(3) singlet, where the $\Lambda(1670)$ and $\Lambda(1690)$ are assigned to the octet. In this presentation, we will present differential cross sections for these excited $\Lambda$ states, $\Lambda(1520)$, $\Lambda(1670)$ and $\Lambda(1690)$, using the photoproduction data from the CLAS detector at Jefferson Lab. [Preview Abstract] |
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