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Nuclear Theory·nucl-th

Tuesday·November 9, 2021

14 papers—6 primary·8 cross-listed

All14Primary6Cross-lists8
  1. 01

    [Submitted on 8 Nov 2021]

    Dynamic effects of nuclear surface in isoscalar dipole modes

    V. I. Abrosimov · O. I. Davydovska

    Dynamic surface effects in the isoscalar dipole modes of heavy nuclei are studied within a semiclassical model based on the solution of the Vlasov kinetic equation for finite Fermi systems with a moving surface. In order to clarify the role of dynamic surface effects we have considered an approximate solution, which takes into account only the part of the variation of the phase-space distribution function caused by the dynamic surface (the dynamic-surface approximation). It is shown that the dynamic surface effects have an essential influence on the features of the isoscalar dipole modes. The isoscalar dipole strength function has a two-resonance structure already in the dynamic-surface approximation, and the centroid energies of both the low-energy resonance and the high-energy resonance are close to corresponding centroid energies of exact strength function. Calculations of the velocity field in the dynamic-surface approximation show the vortex character of the low-energy isoscalar dipole resonance and the compression character of the high-energy one.

    Comments:
    15 pages, 4 figures, typos correct
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2111.04218 [pdf]
    NPA(2023)·0 citations
  2. 02

    [Submitted on 8 Nov 2021]

    Dineutron in the state of He

    Shoya Ogawa · Takuma Matsumoto

    We investigate the dineutron in the state of He via analysis of its decay mode by using the complex scaling method. In this letter, we propose the cross section for the resonant state to distinguish the resonant contributions from the nonresonant ones. As the results, it is found that the shoulder peak appears in the cross section for the resonant state as a function of . Furthermore, we show that the = 0 component of the cross section, where is the total spin of the valence two neutrons, has a peak around the shoulder peak, which comes from the dineutron configuration in the state. Thus we conclude that the shoulder peak is expected to indicate the existence of the dineutron in the state.

    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2111.04285 [pdf]
    PRC(2022)·2 citations
  3. 03

    [Submitted on 8 Nov 2021]

    Can we decipher the composition of the core of a neutron star?

    Chiranjib Mondal🇫🇷 · Francesca Gulminelli🇫🇷

    General relativity guarantees a unique one-to-one correspondence between static observables of neutron stars (NSs) accessible by multi-messenger astronomy, such as mass-radius or tidal deformability, and the equation of state (EoS) of beta equilibrated matter. It is well known that these static properties are not enough to discern conventional NSs from hybrid stars. However, if one assumes that hadrons present in the neutron star core are only neutrons and protons, the lepton fraction is in principle determined unequivocally by the condition of chemical equilibrium. Using a simple analytical method based on a polynomial expansion of the EoS, we show that multiple solutions are possible to the beta-equilibrium equation, leading to a characteristic indetermination on the composition of the interiors of NSs, even in the purely nucleonic hypothesis. We further show that additional empirical information on symmetric matter at high densities are not very efficient to pin down the composition, if uncertainties on measurements are accounted for. We conclude that constraints on the symmetry energy at high densities only, can make meaningful impact to decipher the composition of neutron star core. Our results give a lower limit to the uncertainty on the NS core composition that can be obtained with astrophysical and terrestrial experiments.

    Comments:
    8 pages, restructured, new figures added
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
    arXiv:
    2111.04520 [pdf]
    PRD(2022)·42 citations
  4. 04

    [Submitted on 8 Nov 2021]

    Systematic shell-model study on spectroscopic properties in the south region of Pb

    Cenxi Yuan · Menglan Liu · Noritaka Shimizu · Zs. Podolyak · Toshio Suzuki · Takaharu Otsuka · Zhong Liu

    We aim to study the properties of nuclei in the south region of Pb systematically, including the binding and excitation energies and electromagnetic properties, in order to predict unknown properties of these nuclei, such as isomerism, utilizing a theoretical model which describes the experimentally known properties precisely. We also address whether the shell closure is robust or not when the proton number decreases from Pb. We performed large-scale shell-model calculations with a new Hamiltonian suggested in the present work. The model space is taken as the five proton orbits within and the thirteen neutron orbits within . And one-particle one-hole excitation is allowed across the gap. The Hamiltonian is constructed by combining the existing Hamiltonians, KHHE (with adjustment of its proton-proton part) and KHPE, and the monopole based universal interaction. The shell-model results well reproduce the experimentally observed binding energies and spectroscopic properties, such as isomerism, core excitation, and electromagnetic properties. Some possible isomeric states in neutron-rich Pb, Tl, and Hg isotopes are predicted with transition energies and half-lives. We also examine the effective charges and the quenching of the factors suitable for this region by systematic comparisons between observed and calculated electromagnetic properties. A new Hamiltonian is constructed for nuclei in the south region of Pb, mainly including Pb, Tl, Hg, Au, Pt, Ir, Os, Re, and W isotopes around , and provides them reasonable descriptions on nuclear properties including binding energies, excitation energies and electromagnetic properties through comprehensive and systematic studies.

    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2111.04537 [pdf]
    PRC(2022)·24 citations
  5. 05

    [Submitted on 8 Nov 2021]

    Self-consistent description of high-spin states in doubly magic Pb

    N. Lyutorovich · V. Tselyaev · J. Speth · G. Martinez-Pinedo · K. Langanke · P.-G. Reinhard

    We analyze recent data on a long series of high-spin states in Pb with a self-consistent phonon-coupling model for nuclear excitations based on the Skyrme functionals. The model is the renormalized time-blocking approximation (RenTBA) which takes the coherent one-particle-one-hole (1p1h) states of the random-phase approximation (RPA) as starting point and develops from that more complex configurations beyond RPA. To the best of our knowledge, this is the first investigation of high spin states in Pb using self-consistent nuclear models. The interesting point here is that complex configurations are compulsory to describe the upper end of the long spin series at all. The data thus provide an ideal testing ground for phonon-coupling models as they give direct access to complex configurations. We find that standard Skyrme functionals which perform well in ground state properties and giant resonance excitations deliver at once an agreeable description of these high spin states.

    Comments:
    7 pages, 2 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2111.04602 [pdf]
    PRC(2022)·1 citation
  6. 06

    [Submitted on 8 Nov 2021]

    Nuclear DFT analysis of electromagnetic moments in odd near doubly magic nuclei

    P.L. Sassarini🇬🇧 · J. Dobaczewski🇬🇧 · J. Bonnard🇬🇧 · R.F. Garcia Ruiz🇺🇸

    We use the nuclear density functional theory to determine nuclear electric quadrupole and magnetic dipole moments in all one-particle and one-hole neighbours of eight doubly magic nuclei. We align angular momenta along the intrinsic axial-symmetry axis with broken time-reversal symmetry, which allows us to explore fully the self-consistent charge, spin, and current polarisation. Spectroscopic moments are determined for symmetry-restored wave functions and compared with available experimental data. We find that the obtained polarisations do not call for using quadrupole- or dipole-moment operators with effective charges or effective g-factors.

    Comments:
    16 LaTeX pages, 6 figures, extended version, accepted as a Letter in Journal of Physics G
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2111.04675 [pdf]
    J.Phys.G(2022)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE