Bulletin of the American Physical Society
2021 Fall Meeting of the APS Division of Nuclear Physics
Volume 66, Number 8
Monday–Thursday, October 11–14, 2021; Virtual; Eastern Daylight Time
Session FG: Mini-Symposium: Short Range Correlations in Nuclei III |
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Chair: Dien Nguyen, Jefferson Lab Room: Copley & Kenmore |
Tuesday, October 12, 2021 2:00PM - 2:36PM |
FG.00001: Short-Range Correlations Studies using Nucleon-knockout Reactions Invited Speaker: Igor Korover During the last decade, nucleon knockout reactions have been a very powerful tool to investigate short range correlated (SRC) nucleon-nucleon pairs. SRC pairs account for almost all the high-momentum nucleons in nuclei. Studying SRCs can help us understand the nucleon-nucleon (NN) interaction at high momenta and short distances, the structure of nucleons and nuclei, neutrino-nucleus interactions needed to interpret oscillation measurements, and the structure of neutron stars. |
Tuesday, October 12, 2021 2:36PM - 2:48PM |
FG.00002: A new measurement of the EMC effect in 9Be, 10B, and 11B. Abishek Karki Experiment E12-10-008 will measure inclusive electron scattering from a large range of nuclei to obtain their nuclear structure function. The experiment aims to extract the ratio of the structure function to deuterium to measure the EMC effect. Part of the experiment was carried out in Hall C at JLab, during spring 2018, acquiring data on Be, 10B, 11B, and C. This experiment is the first measurement of the EMC ratio for the light nuclei 10B and 11B, which will help test the idea that the local nuclear density plays an important role in quark modification in the nuclear medium. In this talk, I will be showing some preliminary results and our current analysis. |
Tuesday, October 12, 2021 2:48PM - 3:00PM |
FG.00003: Short-Range Correlation ratio measurements in Hall C at JLab Casey A Morean, Nadia Fomin Short-range correlations (SRCs) are known to be a major component of the high-momentum tail in nuclei. SRCs are formed due to the strongly repulsive core of the nucleon-nucleon potential. A linear correlation between SRC pairs and the EMC effect became evident from the 6 GeV experiments at JLab. During the commissioning of the super high momentum spectrometer, several nuclear targets were studied, including boron-10, boron-11 and beryllium. The status of data analysis will be discussed and preliminary results shown. |
Tuesday, October 12, 2021 3:00PM - 3:12PM |
FG.00004: Probing the Deuteron for Intrinsic Deltas Hang Qi The deuteron is an ideal object for testing non-nucleonic degrees of freedom, because the theory of Delta-Delta pair in the deuteron is well-defined, and the measurement allows exclusivity. We study the use of quasi-elastic electron scattering from intrinsic Delta in a deuteron to provide an exclusive measurement of the intrinsic Delta-Delta configuration in the deuteron. This talk will present preliminary results from Monte Carlo simulations of electron Delta quasi-elastic scattering process in CLAS 12 detector. |
Tuesday, October 12, 2021 3:12PM - 3:24PM |
FG.00005: Probing Short Range Correlations with Real Photon Beams Sandra Santiesteban Exclusive and semi-inclusive electron scattering experiments continue to be one of the best tools for learning about short-range correlations (SRCs) in nuclei. At the same time, the interpretation of these experiments relies on a common understanding of the reaction mechanisms at high momentum transfer. Therefore, new techniques are being developed to fully understand SRC pairs independently of the reaction. This talk introduces the Hall D SRC/CT experiment, which is the first experiment that will use a real photon as a probe in nuclear targets to study SRC, and it will also include measurement of color transparency. It will be performed in Jefferson Lab at the end of the Fall of 2021, and it aims to measure a wide range of reaction channel. In particular, the pγ→ρp channel simulation will be discussed to understand the expected results and the possible impact of the experiment. |
Tuesday, October 12, 2021 3:24PM - 3:36PM |
FG.00006: Using Generalized Contact Formalism and Real Photon Beams to Explore Short Range Nuclear Structure Phoebe Sharp Generalized Contact Formalism (GCF), a scale-separated theoretical framework for describing short-range correlations (SRC) in nuclei, has proven to be a powerful tool for interpreting electron scattering experiments. From these experiments, GCF has helped us learn about isospin structure of SRC pairs, nuclear spectral functions, short-range nucleon-nucleon (NN) forces, and other phenomena. A key prediction is that, for sufficiently hard scattering, the interaction of the probe and a nucleon can be factorized from the interactions of nucleons within a SRC pair, which themselves factorize from the interactions between the pair and the rest of the nucleus. The upcoming Hall D Short- Range Correlations / Color Transparency Experiment will be able to put this prediction to the test by probing short range correlations using a real photon beam. This talk will discuss the application of GCF to a real photon beam and predictions of this experiment through a GCF context. |
Tuesday, October 12, 2021 3:36PM - 3:48PM |
FG.00007: Evaluation of Photo-Disintegration Cross-Section for Light Nuclei Using SRC Based Approach Ranjeet Dalal, Dinesh Negi, Rajesh Beniwal The SRC presence in nuclei has been confirmed with a wide variety of probes which include photons, pions, and multi-GeV electron and proton beams. These observations have stimulated a range of phenomenological/theoretical models including Quasi-Deuteron Model (QDM), the Independent Pair Model (IPAM), the 2N interaction model for pion interaction, and a recently proposed contact formalism. The required SRC percentile inside nuclei varies for different probes. In QDM for N=Z nuclei, it is about 50% of all nucleons (=NZ/A) and it accounts, as high as, 70% of pion absorption events (through 2N reaction mechanism). In this work, we propose an extension of IPAM in which the nucleons are assumed in 2-body/3-body SRCs instead of independently moving nucleons in mean-field. Apart from encompassing the above mentioned SRC observations, the current approach is also expected to provide an understanding of the cluster observations (since the paired n-p SRCs would be equivalent to quasi-alpha structures) and binding energy saturation (since the fundamental NN interaction in the SRC formation remains the same) in nuclei. Here, we have employed this approach to calculate the total photo-disintegration cross-section of N=Z light nuclei for Eγ ranging from 10 to 140 MeV. The photodisintegration process is assumed to be due to the quasi-deuteron/np-SRC and quasi-alpha degree of freedom. The photo-disintegration cross-section of quasi-deuterons/np-SRCs is evaluated by scaling the well-known expressions for free deuterons while that of quasi-alpha structures is estimated by Gunn-Irving photo-disintegration formulation. A significant fraction of the photo-disintegration cross-section in the GDR region may be accounted for by the contribution of quasi-α degree of freedom which decreases with higher Eγ. The derivation of the Levinger formula is obtained without any additional assumptions. The present work suggests an alternative and viable description of photodisintegration for N=Z nuclei. |
Tuesday, October 12, 2021 3:48PM - 4:00PM |
FG.00008: Phase-space distributions of nuclear short-range correlations Wim Cosyn, Jan Ryckebusch Nuclear short-range correlations (SRC) induce high-momentum/high-energy fluctuations in the nuclear medium. In order to assess the impact of SRC on nuclear bulk properties, it is instrumental to determine how SRC are distributed in phase space as this sheds light on the connection between the appearance of SRC in coordinate and momentum space. Using the lowest-order correlation operator approximation (LCA) to include SRC, we compute two-dimensional nuclear Wigner quasiprobability distributions w(r,k) to locate those (r,k) phase-space regions that are most heavily impacted by SRC. The SRC-induced high-momentum components find their origin in a radial range that is confined to the nuclear interior. As an application of w(r,k), we focus on the radial dependence of the kinetic energy T and the momentum dependence of the nucleon radius rrms for the symmetric nuclei 12C, 40Ca and the asymmetric nucleus 48Ca. The kinetic energy almost doubles after including SRCs, with the largest increase occurring in the nuclear interior r≲2 fm. The momentum dependence of the rrms teaches that the largest contributions stem from k≲2 fm−1, where the SRC induce a slight reduction of the order of a few percent. The SRC systematically reduce the 48Ca neutron skin by an amount that can be 10%. |
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