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Nuclear Theory·nucl-th

Monday·April 24, 2023

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    [Submitted on 20 Apr 2023]

    Executive Summary of the Topical Program: Nuclear Isomers in the Era of FRIB

    G. W. Misch · M. R. Mumpower · F. G. Kondev · S. T. Marley · S. Almaraz-Calderon · M. Brodeur · B. A. Brown · M. P. Carpenter · J. J. Carroll · C. J. Chiara · K. A. Chipps · B. P. Crider and 20 other authors

    We report on the Facility for Rare Isotope Beams (FRIB) Theory Alliance topical program "Nuclear Isomers in the Era of FRIB". We outline the many ways isomers influence and contribute to nuclear science and technology, especially in the four FRIB pillars: properties of rare isotopes, nuclear astrophysics, fundamental symmetries, and applications for the nation and society. We conclude with a resolution stating our recommendation that the nuclear physics community actively pursue isomer research. A white paper is forthcoming.

    Comments:
    4 pages including references
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2304.10608 [pdf]
    1 citation
  2. 02

    [Submitted on 21 Apr 2023]

    Quasiparticle resonance in decay spectrum of unbound nuclei near neutron drip-line

    Yoshihiko Kobayashi · Masayuki Matsuo

    Background: The pairing correlation in weakly bound nuclei causes a mixing among bound and unbound configurations. A remarkable consequence is emergence of the quasiparticle resonance, which has been predicted with the coordinate space Hartree-Fock-Bogoliubov (HFB) theory, but not yet observed experimentally. Purpose: We discuss possible observation of quasiparticle resonances in decay spectrum of unbound nuclei near the neutron drip-line. We deal with an example of unbound nucleus C which disintegrates to C and a neutron. Method: We describe a scattering state consisting of C and a neutron in the framework of the HFB formalism. We assume that a nucleon knockout reaction produces a doorway state of the decay, and we evaluate the decay spectrum by taking an overlap of the doorway state and the scattering state of . A numerical calculation was performed with the Woods-Saxon potential and a density-dependent effective pairing interaction. Results: We show that the quasiparticle resonance appears as low-lying peaks in the decay spectrum of C. They originate from the weakly bound single-neutron orbits and , but emerge as unbound resonant quasiparticle states under the influence of the neutron pairing correlation. The resonance energy and the width of the calculated quasiparticle resonances are consistent with an experimental observation whereas they are sensitive to the neutron pairing correlation. Conclusion: The results suggest that nucleon knockout reactions populating the unbound nucleus provide realistic opportunity of experimentally observing the quasiparticle resonance and of disclosing the pairing correlation in neutron-rich nuclei.

    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2304.10787 [pdf]
    PRC(2023)·1 citation
  3. 03

    [Submitted on 21 Apr 2023]

    Moments of inertia in light deformed nuclei: pairing and mean-field impacts

    V.O. Nesterenko · M.A. Mardyban · P.-G. Reinhard · A. Repko · J. Kvasil

    The dependence of the moment of inertia on the pairing and axial quadrupole deformation in Mg and Ne was investigated. The study is based on quadrupole-constrained calculations with three cranking approaches for (Inglis-Belyaev, Thouless-Valatin, adiabatic time-dependent Hartree-Fock) and a representative set of Skyrme forces (SVbas, SkM*, SLy6). At variance with macroscopic collective models, the calculations predict the specific regime at (Mg) and (Ne), where the pairing breaks down. This regime is explained by two effects: full break up of the pairing and specific evolution of a {\it single} dominant particle-hole (1ph) configuration with . The analysis of experimental data for the ground-state rotational bands in Mg and Ne shows that such regime is possible at low spins.

    Comments:
    17 pages, 8 figures; refs. [15,16] were added as compared with the previous version
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2304.10873 [pdf]
    IJMPE(2024)·1 citation
  4. 04

    [Submitted on 21 Apr 2023]

    and Freeze-Out Distributions and Global Polarizations in Au+Au Collisions

    Nikita Tsegelnik (JINR)🇷🇺 · Evgeni Kolomeitsev (JINR, Matej Bel University)🇷🇺 · Vadym Voronyuk (JINR)🇷🇺

    The gold--gold collisions at and GeV are simulated within the PHSD transport model. In each collision event, the spectator nucleons are separated and the fluidization procedure for the participants is performed. The local velocities are determined in the Landau frame and the kinematic and thermal vorticity fields are evaluated. We analyze the thermodynamic properties of the cells where s and s were born or had their last interaction. Such cells contribute to the formation of the observed global polarization of hyperons induced by the thermal vorticity of the medium. The polarization signal is found to be mainly determined by hot, dense, and highly vortical cells at the earlier stage of the collision, whereas the polarization signal is accumulated over the longer time and includes cells with lower vorticity. The calculated global polarizations for both s and s agree well with the experimental finding by the STAR collaboration at energy GeV. For collisions at GeV, we can reproduce the STAR data for hyperons, but significantly underpredict the observed global polarization of . Furthermore, we consider the centrality dependence of the hyperon polarization in collisions at 7.7GeV. It increases with an increase of centrality, reaches a maximum at 65--75%, and then starts decreasing rapidly for peripheral collisions.

    Comments:
    12 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2304.10998 [pdf]
    Particles(2023)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE