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Nuclear Theory·nucl-th

Thursday·July 23, 2020

8 papers—3 primary·5 cross-listed

All8Primary3Cross-lists5
  1. 01

    [Submitted on 22 Jul 2020]

    Nucleus giant resonances from an improved isospin-dependent Boltzmann-Uehling-Uhlenbeck transport approach

    Jun Xu · Wen-Tao Qin

    We have studied the isoscalar giant quadruple resonance (ISGQR) and the isovector giant dipole resonance (IVGDR) in Pb based on an improved isospin-dependent Boltzmann-Uehling-Uhlenbeck transport approach using an improved isospin- and momentum-dependent interaction. With the isoscalar nucleon effective mass and the nucleon-nucleon cross section which reproduces respectively the excitation energy and the width of the ISGQR strength function, the slope parameter of the symmetry energy and the neutron-proton effective mass splitting are constrained respectively within MeV and , by comparing the resulting centroid energy of the IVGDR and the electric dipole polarizability with the experimental data. It is found that nucleon-nucleon collisions have considerable effects on the resulting electric dipole polarizability, which needs to be measured more accurately in order to pin down isovector nuclear interactions.

    Comments:
    10 pages, 7 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2007.11194 [pdf]
    PRC(2020)·22 citations
  2. 02

    [Submitted on 22 Jul 2020]

    Comment on "Quasielastic lepton scattering and back-to-back nucleons in the short-time approximation", by S. Pastore et al

    Omar Benhar

    The article of Pastore et al, while proposing an interesting and potentially useful approach for the generalisation of Quantum Monte Carlo techniques to the treatment of the nuclear electromagnetic response, features an incorrect and misleading discussion of y-scaling. The response to interactions with transversely polarised virtual photons receives sizeable contributions from non-scaling processes, in which the momentum transfer is shared between two nucleons. It follows that, contrary to what is stated by the the authors, y-scaling in the transverse channel is accidental.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2007.11237 [pdf]
    PRC(2022)·2 citations
  3. 03

    [Submitted on 22 Jul 2020]

    Perturbative Approach to Effective Shell-Model Hamiltonians and Operators

    L. Coraggio🇮🇹 · N. Itaco🇮🇹

    The aim of this work is to present an overview of the derivation of the effective shell-model Hamiltonian and decay operators within many-body perturbation theory, and to show the results of selected shell-model studies based on their utilisation. More precisely, we report some technical details that are needed by non-experts to approach the derivation of shell-model Hamiltonians and operators starting from realistic nuclear potentials, in order to provide some guidance to shell-model calculations where the single-particle energies, two-body matrix elements of the residual interaction, effective charges and decay matrix elements, are all obtained without resorting to empirical adjustments. On the above grounds, we will present results of studies of double-beta decay of heavy-mass nuclei where shell-model ingredients are derived from theory, so to assess the reliability of such a way to shell-model investigations. Attention will be also focussed on the relevant aspects that are connected to the behavior of the perturbative expansion, whose knowledge is needed to establish limits and perspectives of this approach to nuclear structure calculations.

    Comments:
    39 pages, 18 figures, 3 tables, to be published in Frontiers in Physics as a contribution to the Research Topic "The Future of Nuclear Structure: Challenges and Opportunities in the Microscopic Description of Nuclei"
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2007.11470 [pdf]
    Front.in Phys.(2020)·37 citations

Affiliations

first authorsco-authorsvia INSPIRE