Bulletin of the American Physical Society
APS April Meeting 2020
Volume 65, Number 2
Saturday–Tuesday, April 18–21, 2020; Washington D.C.
Session J11: Mini-Symposium: QCD and the Nuclear MediumFocus Live
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Chair: Douglas Higinbotham, Jefferson Lab Room: Maryland A |
Sunday, April 19, 2020 1:30PM - 2:06PM Live |
J11.00001: From Quarks to Nuclei from JLab to the EIC Invited Speaker: Florian Hauenstein Understanding the modification of quarks in nucleons within nuclei (EMC effect) is a longstanding open question in nuclear physics. Recent experimental results from electron scattering at Jefferson Lab strengthen the correlation between the EMC effect and short- range correlated pairs (SRC) of nucleons in nuclei. That means that the EMC effect is probably driven by the high-momentum highly-virtual nucleons of the SRC pairs. This connection can be tested experimentally by measuring electron deep inelastic scattering from a nucleon and detecting its correlated SRC partner nucleon (tagging). This allows us to measure the quark modification as a function of nucleon virtuality. Two tagged experiments on deuterium are underway at Jefferson Lab of which one already took data and the other will take data in the upcoming years. These experiments can be naturally extended to the Electron-Ion Collider (EIC) whose unique capabilities allow for higher Q2 and much easier detection of the tagged recoil nucleon. In my talk, I will present the current knowledge of the EMC effect and its correlation to SRC pairs, the status of the tagged measurements at Jefferson Lab, and simulation results for tagged measurements at the EIC. [Preview Abstract] |
Sunday, April 19, 2020 2:06PM - 2:18PM Live |
J11.00002: Transverse momentum broadening studies of Drell-Yan dimuons at the SeaQuest experiment Arun Tadepalli In Drell-Yan reactions producing final state dimuons, the transverse momentum of the dimuon, $p_{T}$, is nearly an independent variable that makes measurements in the transverse direction. Multiple interactions of the parton traversing a nuclear medium leads to the broadening of the transverse momentum. In many models this broadening is also associated with energy loss of the incident beam parton participating in the reaction. With minimal final state interactions, the Drell-Yan process is an ideal probe to study broadening of the transverse momentum which could give an insight into the interactions of fast quarks in cold nuclear matter and serve as an important benchmark for properties of matter created in heavy ion collisions. Fermilab E772, E789 and E866 experiments have all studied $p_{T}$ broadening with a 800 GeV proton beam. The SeaQuest/E906 experiment uses a 120 GeV/c proton beam extracted from the Main Injector at Fermilab to collide with carbon, iron, tungsten and liquid deuterium targets. Data at the relatively lower energy compared to the previous Drell-Yan experiments is expected to be more sensitive to quark propagation effects. Current status of the analysis will be reported in the talk. [Preview Abstract] |
Sunday, April 19, 2020 2:18PM - 2:30PM Live |
J11.00003: Chiral Effective Field Theory calculations of weak transitions in light nuclei Garrett King, Saori Pastore, Maria Piarulli, Rocco Schiavilla, R. B. Wiringa We present {\it ab initio} calculations of weak transitions in $A\le 10$ nuclei--including beta decays of $^{6}$He, $^{8}$Li, $^{8}$B, $^{8}$He, and $^{10}$C and electron-capture in $^{7}$Be--using Variational and Green's Function Monte Carlo methods. Calculations of matrix elements employ the Norfolk potential, a high-quality local chiral interaction containing two- ($NN$) and three-body ($3N$) forces, and consistent one- and two-body axial currents. We investigate the sensitivity of the matrix elements to choices of different cutoffs and different strategies to constrain the $NN$ and $3N$ potentials. For $A < 10$, the inclusion of two-body axial currents results in a small additive contribution to the one-body matrix element for these various choices, except for in the $A=8$ systems where we find a significant contribution from two-body axial currents. In the case of $A=10$, we find that our results vary depending on the adopted nuclear interactions. In addition, we present calculations of one- and two-body transition densities. These studies provide a validation of nuclear many-body correlations and currents entering {\it ab initio} calculations and impact studies of neutrinoless double beta decay and searches for beyond standard model physics. [Preview Abstract] |
Sunday, April 19, 2020 2:30PM - 2:42PM Live |
J11.00004: Theoretical uncertainty for neutrinoless double-beta decay from chiral EFT Eduardo Coello Perez We study the neutrinoless double-beta decay of germanium 76 in a model that describes the parent and daughter nuclei as four valence nucleons on top of a germanium 72 core. The valence nucleons interact with each other via chiral nucleon-nucleon and three-nucleon interactions, while in-medium effects are modeled as an effective core-nucleon interaction. These interactions are fitted to reproduce neutron-proton phase shifts, deuteron binding energy, and the binding energies of the nuclei of interest as well as the energies of their first excited 0+ states. We employ Markov-chain Monte Carlo sampling to generate distributions for the low-energy constants of the chiral nucleon-nucleon contact interaction. The wave functions for the relevant ground states resulting from each set of parameters is employed to calculate the corresponding neutrinoless double-beta decay matrix element. The resulting distribution for the matrix element possesses a mode in good agreement with traditional shell-model calculations. The associated theoretical uncertainty comes from the interval with 95% degree-of-belief. [Preview Abstract] |
Sunday, April 19, 2020 2:42PM - 2:54PM |
J11.00005: Results from Kinematically Complete Photodisintegration of 3He Forrest Friesen, Mohammad Ahmed, Alex Crowell, Arnas Deltuva, Calvin Howell, Collin Malone, Ron Malone, Werner Tornow, Henryk WitaĆa Kinematically complete measurements of acceptance integrated photodisintegration cross sections were performed with a 15 MeV photon beam at the high intensity $\gamma$-ray source. The $^3$He($\gamma$,pn)p, $^3$He($\gamma$,pp)n, $^3$He($\gamma$,p)np three-body photodisintegration reactions were measured concurrently. Neutrons were detected over the range of laboratory polar angles from about 30$^\circ$ to 150$^\circ$. Events corresponding to the np final state interaction were selected using the angle between the neutron and proton in np coincidences. The target beam luminosity was measured in-situ using the $^3$He($\gamma$,p)d two-body photodisintegration reaction. There was good agreement between GEANT4 simulations based on ab-initio three-nucleon calculations and measurements in the vicinity of the np collinear point (i.e., the proton at rest in the cm frame). The experiment techniques will be described and results for several exit-channel configurations in three-body photodisintegration will be presented. [Preview Abstract] |
Sunday, April 19, 2020 2:54PM - 3:06PM Not Participating |
J11.00006: Event reconstruction for the upcoming Super BigBite Spectrometer program in JLab's Hall A Andrew Puckett The common collection of experimental apparatus known as the Super BigBite Spectrometer (SBS), slated for installation in Jefferson Lab's Hall A in 2020, will facilitate a highly anticipated program of measurements of nucleon electromagnetic form factors at large $Q^2$, transverse single-spin asymmetries in Semi-Inclusive Deep Inelastic Scattering (SIDIS), and future novel measurements such as the pion structure function from tagged DIS. The enabling technology for this physics program is the high-rate charged-particle tracking technology of Gas Electron Multipliers (GEMs), which can operate with large solid-angle acceptance in the high-luminosity environment of Hall A, with direct line of sight from the target to the detectors. The major challenge for event reconstruction in the SBS experiments is the high rate of soft photon-induced random background hits in the GEMs, which is overcome using a combination of constraints on the particle tracks of interest from total-absorption calorimeters and other PID detectors, and/or exclusivity of the reaction kinematics. In this talk, I will provide an overview of the tracking challenge facing the SBS experiments, the methods for overcoming those challenges, and the present status and performance of the SBS event reconstruction software. [Preview Abstract] |
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