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Nuclear Theory·nucl-th

Friday·November 12, 2021

6 papers—4 primary·2 cross-listed

All6Primary4Cross-lists2
  1. 01

    [Submitted on 10 Nov 2021]

    Prediction of the excitation energies of the 2 states for superheavy nuclei based on the microscopically derived Grodzins relation

    N.Yu. Shirikova · A.V. Sushkov · L.A. Malov · E.A. Kolganova · R.V. Jolos

    As the result of synthesis of nuclei with large proton numbers a new region of investigations of the structure of nuclei has been discovered. Due to the recent significant increase in the yield of superheavy nuclei their gamma-spectroscopic studies became possible. The purpose of paper is to predict the excitation energies of the states of nuclei with Z using the microscopic variant of the Grodzins relation derived based on the geometrical collective model. The excitation energies of the states of the even-even nuclei from Fm to X which differ from each other in the number of -particles are predicted. It is shown that at the beginning of the chain of the studied nuclei the excitation energies of the states don't exceed 100 keV. Then sharply increases with and reaches maximum value of keV in Fl or Og.

    Comments:
    7 pages, 2 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2111.05919 [pdf]
    PRC(2022)·6 citations
  2. 02

    [Submitted on 10 Nov 2021]

    Fixed-Point Few-Body Hamiltonians in Quantum Mechanics

    Lauro Tomio🇧🇷 · Tobias Frederico🇧🇷 · Varese S. Timóteo🇧🇷 · Marcelo T. Yamashita🇧🇷

    We revisited how Weinberg's ideas in Nuclear Physics influenced our own work and lead to a renormalization group invariant framework within the quantum mechanical few-body problem, and we also update the discussion on the relevant scales in the limit of short-range interactions. In this context, it is revised the formulation of the subtracted scattering equations and fixed-point Hamiltonians applied to few-body systems, in which the original interaction contains point-like singularities, such as Dirac-delta and/or its derivatives. The approach is being illustrated by considering two-nucleons described by singular interactions. This revision also includes an extension of the renormalization formalism to three-body systems, which is followed by an updated discussion on the applications to four particles.

    Comments:
    27 pages, 2 figures
    Subjects:
    Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2111.05954 [pdf]
    Few Body Syst.(2022)·0 citations
  3. 03

    [Submitted on 11 Nov 2021]

    Neutron star properties with careful parameterization in the (axial)vector meson extended linear sigma model

    Péter Kovács🇭🇺 · János Takátsy🇭🇺 · Jürgen Schaffner-Bielich🇩🇪 · György Wolf🇭🇺

    The existence of quark matter inside the cores of heavy neutron stars is a possibility which can be probed with modern astrophysical observations. We use an (axial)vector meson extended quark-meson model to describe quark matter in the core of neutron stars. We discover that an additional parameter constraint is necessary in the quark model to ensure chiral restoration at high densities. By investigating hybrid star sequences with various parameter sets we show that low sigma meson masses are needed to fulfill the upper radius constraints, and that the maximum mass of stable hybrid stars is only slightly dependent on the parameters of the crossover-type phase transition. Using this observation and results from recent astrophysical measurements a constraint of 2.6 < g_V < 4.3 is set for the constituent quark - vector meson coupling. The effect of a nonzero bag constant is also investigated and we observe that its effect is small for values adopted in previous works.

    Comments:
    15 pages, 12 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2111.06127 [pdf]
    PRD(2022)·22 citations
  4. 04

    [Submitted on 11 Nov 2021]

    A modified Brink-Axel hypothesis for astrophysical Gamow-Teller transitions

    Raul A. Herrera · Calvin W. Johnson · George M. Fuller

    Weak interaction charged current transition strengths from highly excited nuclear states are fundamental ingredients for accurate modeling of compact object composition and dynamics, but are difficult to obtain either from experiment or theory. For lack of alternatives, calculations have often fallen back upon a generalized Brink-Axel hypothesis, that is, assuming the strength function (transition probability) is independent of the initial nuclear state but depends only upon the transition energy and the weak interaction properties of the parent nucleus ground state. Here we present numerical evidence for a modified `local' Brink-Axel hypothesis for Gamow-Teller transitions for -shell nuclei relevant to astrophysical applications. Specifically, while the original Brink-Axel hypothesis does not hold globally, strength functions from initial states nearby in energy are similar within statistical fluctuations. This agrees with previous work on strength function moments. Using this modified hypothesis, we can tackle strength functions at previously intractable initial energies, using semi-converged initial states at arbitrary excitation energy. Our work provides a well-founded method for computing accurate thermal weak transition rates for medium-mass nuclei at temperatures occurring in stellar cores near collapse. We finish by comparing to previous calculations of astrophysical rates.

    Comments:
    19 pages, 10 figures; updated to better match final version
    Subjects:
    Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Computational Physics (physics.comp-ph)
    arXiv:
    2111.06242 [pdf]
    PRC(2022)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE