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Nuclear Theory·nucl-th

Thursday·October 13, 2022

7 papers—5 primary·2 cross-listed

All7Primary5Cross-lists2
  1. 01

    [Submitted on 11 Oct 2022]

    Constraining Neutrinoless Double-Beta Decay Matrix Elements from Ab Initio Nuclear Theory

    A. Belley🇨🇦 · T. Miyagi🇩🇪 · S. R. Stroberg🇺🇸 · J. D. Holt🇨🇦

    As experimental searches for neutrinoless double-beta () decay are entering a new generation, with hopes to completely probe the inverted mass hierarchy, the need for reliable nuclear matrix elements, which govern the rate of this decay, is stronger than ever. Since a large discrepancy in results is typically found with nuclear modela, a large unknown still exists on the sensitivity of these experiments to the effective neutrino mass. We consider this problem from a first-principles perspective, using the ab initio valence-space in medium similarity renormalization group. In particular, we study correlations of the -decay matrix elements in Ge with other observables, such as the double Gamow-Teller giant resonance, from 34 input chiral interactions in an attempt to constrain our uncertainties and investigate the interaction dependence of the nuclear matrix element.

    Comments:
    4 pages, 1 figure, contribution to MEDEX'22
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2210.05809 [pdf]
    AIP Conf.Proc.(2025)·10 citations
  2. 02

    [Submitted on 12 Oct 2022]

    A Problem in the Statistical Description of Beta-Delayed Neutron Emission

    Oliver Gorton · Calvin Johnson · Jutta Escher

    Reaction measurements on fission products are being planned at both Argonne National Lab and at the Facility for Rare Isotope Beams. These indirect experiments produce specific short-lived nuclei via beta decay, and the subsequent neutron and gamma emission are studied. Some initial experiments found a surprising overabundance of gamma emission, which theory has yet to explain. To remedy this, we are developing an integrated nuclear data workflow that connects advanced nuclear shell model codes for describing the beta decay with a contemporary nuclear reaction model code.

    Comments:
    4 pages, 3 figures, proceedings for 15th International Conference on Nuclear Data for Science and Technology (ND2022), version 2 [v2] includes correction to former figure 3 (now figure 4) and figure 2 has been split and modified
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2210.05904 [pdf]
    EPJ Web Conf.(2023)·2 citations
  3. 03

    [Submitted on 12 Oct 2022]

    A local-density-approximation description of high-momentum tails in isospin asymmetric nuclei

    Xiao-Hua Fan · Zu-Xing Yang · Peng Yin · Peng-Hui Chen · Jian-Min Dong · Zhi-Pan Li · Haozhao Liang

    We adapt the local density approximation to add the high-momentum tails (HMTs) to finite nuclei's Slater-determinant momentum distributions. The HMTs are extracted by the extended Brueckner-Hartree-Fock (EBHF) method or by the lowest order cluster approximation. With a correction factor being added to EBHF, it is sufficiently in agreement with the experimental benchmark, i.e., the high-momentum ratios approximately equal to , and the low-momentum ratios approximately equal to of the systems. It is also found that the tensor force makes the nucleon-nucleon correlations appear more easily on the nuclear surface region and the percentage of high-momentum ( MeV/c) nucleons, around --, independent of isospin asymmetry.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2210.05957 [pdf]
    PLB(2022)·6 citations
  4. 04

    [Submitted on 12 Oct 2022]

    Nucleon-nucleon correlations inside atomic nuclei: synergies, observations and theoretical models

    Ranjeet Dalal🇮🇳 · I.J. Douglas MacGregor🇬🇧

    While the main features of atomic nuclei are well described by nuclear mean-field models, there is a large and growing body of evidence which indicates an important additional role played by spatially-correlated nucleon-nucleon structures. The role of nucleonic structures was first suggested by Heidmann in 1950 to explain pick-up reactions of energetic nucleons. Since then a steady flux of new experimental evidence has confirmed the presence of similar structures inside atomic nuclei, dominated by correlations between pairs of nucleons. The role of these internal nucleon-nucleon correlations has been established using various energetic probes like photons, pions, leptons and hadrons. These correlated structures are essential for understanding the interaction of particles with nuclei and their presence provides an explanation of many specific nuclear phenomena including backscattered protons, copious deuteron production, sub-threshold particle production, neutrino interactions with nuclei and the EMC effect. On the theoretical side, these measurements have stimulated a large number of phenomenological models specifically devised to address these enigmatic observations. While reviews exist for specific interactions, there is currently no published commentary which systematically encompasses the wide range of experimental signatures and theoretical frameworks developed thus far. The present review draws together the synergies between a wide range of different experimental and theoretical studies, summarises progress in this area and highlights outstanding issues for further study.

    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2210.06114 [pdf]
    Rept.Prog.Phys.(2024)·10 citations
  5. 05

    [Submitted on 12 Oct 2022]

    Lorentz-covariant nonlocal collision term for spin-1/2 particles

    David Wagner🇩🇪 · Nora Weickgenannt🇩🇪 · Dirk H. Rischke🇩🇪

    We revisit the derivation of the nonlocal collision term in the Boltzmann equation for spin-1/2 particles, using both the Wigner-function approach by de Groot, van Leeuwen, and van Weert, and the Kadanoff-Baym equation in -matrix approximation. Contrary to previous calculations, our results maintain full Lorentz covariance of the nonlocal collision term.

    Comments:
    34 pages, 1 figure
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2210.06187 [pdf]
    PRD(2022)·35 citations

Affiliations

first authorsco-authorsvia INSPIRE