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Nuclear Theory·nucl-th

Monday·February 29, 2016

5 papers—3 primary·2 cross-listed

All5Primary3Cross-lists2
  1. 01

    [Submitted on 25 Feb 2016]

    Equation of state for neutron stars with hyperons by the variational method

    H. Togashi🇯🇵 · E. Hiyama🇯🇵 · Y. Yamamoto🇯🇵 · M. Takano🇯🇵

    We investigate the effects of the odd-state part of bare interactions on the structure of neutron stars (NSs) by constructing equations of state (EOSs) for uniform nuclear matter containing and hyperons with use of the cluster variational method. The isoscalar part of the Argonne v18 two-nucleon potential and the Urbana IX three-nucleon potential are employed as the interactions between nucleons, whereas, as the bare and even-state interactions, two-body central potentials that are determined so as to reproduce the experimental data on single- and double- hypernuclei are adopted. In addition, the interaction is constructed so as to reproduce the empirical single-particle potential of in symmetric nuclear matter. Since the odd-state part of the interaction is not known owing to lack of experimental data, we construct four EOSs of hyperonic nuclear matter, each with a different odd-state part of the interaction. The EOS obtained for NS matter becomes stiffer as the odd-state interaction becomes more repulsive, and correspondingly the maximum mass of NSs increases. It is interesting that the onset density of depends strongly on the repulsion of the odd-state interaction. Furthermore, we take into account the three-baryon repulsive force to obtain results that are consistent with observational data on heavy NSs.

    Comments:
    12 pages, 6 figures, accepted for publication in Phys. Rev. C
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    1602.08106 [pdf]
    PRC(2016)·68 citations
  2. 02

    [Submitted on 26 Feb 2016]

    Global correlations between electromagnetic and spectroscopic properties of collective and states

    Z. Z. Qin · Y. Lei · S. Pittel

    By using the general triaxial rotor model (TRM) and the phonon-configuration mixing scheme within an anharmonic-vibrator(AHV) framework, a series of global correlations between electromagnetic properties of nuclear and states are analytically established. The correlations from both models can roughly describe the experimental data involving quadrupole collectivity with few exceptions. Furthermore, there seems to be a robust orthogonal transformation between the AHV and TRM bases for realistic nuclear systems, suggesting that the two models may in fact be describing the collective features of nuclear low-lying states in similar model spaces.

    Comments:
    8 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1602.08295 [pdf]
    PRC(2016)·2 citations
  3. 03

    [Submitted on 26 Feb 2016]

    Thermodynamics and kinetics of Gribov-Zwanziger plasma with temperature dependent Gribov parameter

    Viktor Begun🇵🇱 · Wojciech Florkowski🇵🇱 · Radoslaw Ryblewski🇵🇱

    A Gribov-type dispersion relation is treated as an effective description of interacting gluons forming a hot medium. Temperature dependence of the Gribov parameter is determined from the fit to the lattice Yang-Mills results describing thermodynamic functions. To maintain thermodynamic consistency of the approach, a temperature dependent bag pressure is introduced. The results obtained for equilibrium functions are generalised in the next step to non-equilibrium conditions. We derive formulas for the bulk and shear viscosity coefficients within the relaxation time approximation. We find evidence for largely enhanced bulk viscosity in the region of the phase transition.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1602.08308 [pdf]
    Acta Phys.Polon.B(2017)·13 citations
  4. 04

    [Submitted on 26 Feb 2016] (cross-list from physics.comp-ph)

    Generation of random deviates for relativistic quantum-statistical distributions

    Boris Tomášik · Ivan Melo · Jakub Cimerman

    We provide an algorithm for generation of momenta (or energies) of relativistic particles according to the relativistic Bose-Einstein or Fermi-Dirac distributions. The algorithm uses rejection method with effectively selected comparison function so that the acceptance rate of the generated values is always better than 0.9. It might find its use in Monte-Carlo generators of particles from reactions in high-energy physics.

    Comments:
    9 pages, 3 figures
    Subjects:
    Computational Physics (physics.comp-ph); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1602.08233 [pdf]
    0 citations
  5. 05

    [Submitted on 26 Feb 2016] (cross-list from hep-ph)

    As the Lightest State

    Richard F. Lebed🇺🇸 · Antonio D. Polosa🇮🇹

    The state has recently been demoted by the Particle Data Group from its previous status as the conventional state, largely due to the absence of expected decays. We propose that is actually the lightest state, and calculate the spectrum of such states using the diquark model, identifying many of the observed charmoniumlike states that lack open-charm decay modes as . Among other results, we argue that is a state that has been not been seen in two-photon fusion largely as a consequence of the Landau-Yang theorem.

    Comments:
    9 pages, pdflatex, version accepted for publication by Phys. Rev. D
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1602.08421 [pdf]
    PRD(2016)·97 citations

Affiliations

first authorsco-authorsvia INSPIRE