PaperPanorama
FAQ

Nuclear Theory·nucl-th

Friday·April 30, 2021

11 papers—3 primary·8 cross-listed

All11Primary3Cross-lists8
  1. 01

    [Submitted on 29 Apr 2021]

    Proton decays in Ne and Mg and isospin-symmetry breaking in carbon isotopes and isotones

    N. Michel🇨🇳 · J. G. Li🇨🇳 · F. R. Xu🇨🇳 · W. Zuo🇨🇳

    Proton-rich nuclei possess unique properties in the nuclear chart. Due to the presence of both continuum coupling and Coulomb interaction, phenomena such as halos, Thomas-Ehrman shift, and proton emissions can occur. Experimental data are difficult to be obtained therein, so that theoretical calculations are needed to understand nuclei at drip-lines and guide experimentalists for that matter. In particular, the Ne and Mg isotopes are supposed to be one-proton and/or two-proton emitting nuclei, but associated experimental data are either incomplete or even unavailable. Consequently, we performed Gamow shell model calculations of carbon isotones bearing . Isospin-symmetry breaking occurring in carbon isotones and isotopes is also discussed. It is hereby shown that the mixed effects of continuum coupling and Coulomb interaction at drip-lines generate complex patterns in isospin multiplets. Added to that, it is possible to determine the one-proton and two-proton widths of Ne and Mg. Obtained decay patterns are in agreement with those obtained in previous experimental and theoretical works. Moreover, up to the knowledge of authors, this is the first theoretical calculation of binding energy and partial decay widths of Mg in a configuration interaction picture.

    Comments:
    12 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2104.14093 [pdf]
    PRC(2021)·23 citations
  2. 02

    [Submitted on 29 Apr 2021]

    Hybrid model with viscous relativistic hydrodynamics: a role of constraints on the shear-stress tensor

    A. S. Khvorostukhin🇷🇺 · E. E. Kolomeitsev🇸🇰 · V. D. Toneev🇷🇺

    We present the hybrid hadron string dynamic (HydHSD) model connecting the parton-hadron-string dynamic model (PHSD) and a hydrodynamic model taking into account shear viscosity within the Israel-Stewart approach. The performance of the code is tested on the pion and proton rapidity and transverse mass distributions calculated for Au+Au and Pb+Pb collision at AGS--SPS energies. The influence of the switch time from transport to hydro models, the viscous parameter, and freeze-out time are discussed. Since the applicability of the Israel-Stewart hydrodynamics assumes the perturbative character of the viscous stress tensor, , which should not exceed the ideal energy-momentum tensor, , hydrodynamical codes usually rescale the shear stress tensor if the inequality is not fulfilled in some sense. We show that the form of the corresponding condition plays an important role in the sensitivity of hydrodynamic calculations to the viscous parameter -- a ratio of the shear viscosity to the entropy density, . It is shown that the constraints used in the vHLLE and MUSIC models give the same results for the observables. With these constraints, the rapidity distributions and transverse momentum spectra are most sensitive to a change of the ratio. As an alternative, a strict condition is used. We performed global fits the rapidity and transverse mass distribution of pion and protons. It was also found that as a function of the collision energy monotonically increases from GeV up to GeV and saturates for higher SPS energies. We observe that it is difficult to reproduce simultaneously pion and proton rapidity distribution within our model with the present choice of the equation of state without a phase transition.

    Comments:
    This paper is the essentially revised version of our paper arXiv:1810.10303
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2104.14197 [pdf]
    EPJA(2021)·8 citations
  3. 03

    [Submitted on 29 Apr 2021]

    Many-body approach to superfluid nuclei in axial geometry

    Yinu Zhang🇺🇸 · Antonio Bjelčić🇭🇷 · Tamara Nikšić🇭🇷 · Elena Litvinova🇺🇸 · Peter Ring🇩🇪 · Peter Schuck🇫🇷

    Starting from a general many-body fermionic Hamiltonian, we derive the equations of motion (EOM) for nucleonic propagators in a superfluid system. The resulting EOM is of the Dyson type formulated in the basis of Bogoliubov's quasiparticles. As the leading contributions to the dynamical kernel of this EOM in strongly-coupled regimes contain phonon degrees of freedom in various channels, an efficient method of calculating phonon's characteristics is required to successfully model these kernels. The traditional quasiparticle random phase approximation (QRPA) solvers are typically used for this purpose in nuclear structure calculations, however, they become very prohibitive in non-spherical geometries. In this work, by linking the notion of the quasiparticle-phonon vertex to the variation of the Bogoliubov's Hamiltonian, we show that the recently developed finite-amplitude method (FAM) can be efficiently employed to compute the vertices within the FAM-QRPA. To illustrate the validity of the method, calculations based on the relativistic density-dependent point-coupling Lagrangian are performed for the single-nucleon states in heavy and medium-mass nuclei with axial deformations. The cases of Si and Cf are presented and discussed.

    Comments:
    Article: 11 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2104.14513 [pdf]
    PRC(2022)·18 citations

Affiliations

first authorsco-authorsvia INSPIRE