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Nuclear Theory·nucl-th

Thursday·July 7, 2016

11 papers—3 primary·8 cross-listed

All11Primary3Cross-lists8
  1. 01

    [Submitted on 14 Jun 2016]

    Equation of state and hybrid star properties with the weakly interacting light U-boson in relativistic models

    Dong-Rui Zhang🇨🇳 · Wei-Zhou Jiang🇨🇳 · Si-Na Wei🇨🇳 · Rong-Yao Yang🇨🇳 · Qian-Fei Xiang🇨🇳

    It has been a puzzle whether quarks may exist in the interior of massive neutron stars, since the hadron-quark phase transition softens the equation of state (EOS) and reduce the neutron star (NS) maximum mass very significantly. In this work, we consider the light U-boson that increases the NS maximum mass appreciably through its weak coupling to fermions. The inclusion of the U-boson may thus allow the existence of the quark degrees of freedom in the interior of large mass neutron stars. Unlike the consequence of the U-boson in hadronic matter, the stiffening role of the U-boson in the hybrid EOS is not sensitive to the choice of the hadron phase models. In addition, we have also investigated the effect of the effective QCD correction on the hybrid EOS. This correction may reduce the coupling strength of the U-boson that is needed to satisfy NS maximum mass constraint. While the inclusion of the U-boson also increases the NS radius significantly, we find that appropriate in-medium effects of the U-boson may reduce the NS radii significantly, satisfying both the NS radius and mass constraints well.

    Comments:
    18 pages, 7 figures
    Subjects:
    Nuclear Theory (nucl-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
    arXiv:
    1607.01610 [pdf]
    EPJA(2016)·8 citations
  2. 02

    [Submitted on 6 Jul 2016]

    Discrete Wave-Packet Representation in Nuclear Matter Calculations

    H. Müther · O.A. Rubtsova · V.I. Kukulin · V.N. Pomerantsev

    The Lippmann-Schwinger equation for the nucleon-nucleon -matrix as well as the corresponding Bethe-Goldstone equation to determine the Brueckner reaction matrix in nuclear matter are reformulated in terms of the resolvents for the total two-nucleon Hamiltonians defined in free space and in medium correspondingly. This allows to find solutions at many energies simultaneously by using the respective Hamiltonian matrix diagonalization in the stationary wave packet basis. Among other important advantages, this approach simplifies greatly the whole computation procedures both for coupled-channel -matrix and the Brueckner reaction matrix. Therefore this principally novel scheme is expected to be especially useful for self-consistent nuclear matter calculations because it allows to accelerate in a high degree single-particle potential iterations. Furthermore the method provides direct access to the properties of possible two-nucleon bound states in the nuclear medium. The comparison between reaction matrices found via the numerical solution of the Bethe-Goldstone integral equation and the straightforward Hamiltonian diagonalization shows a high accuracy of the method suggested. The proposed fully discrete approach opens a new way to an accurate treatment of two- and three-particle correlations in nuclear matter on the basis of three-particle Bethe-Faddeev equation by an effective Hamiltonian diagonalization procedure.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1607.01694 [pdf]
    PRC(2016)·12 citations
  3. 03

    [Submitted on 6 Jul 2016]

    Hydrodynamic flow amplitude correlations in event-by-event fluctuating heavy-ion collisions

    Jing Qian🇨🇳 · Ulrich Heinz🇺🇸

    The effects of event-by-event fluctuations in the initial geometry of the colliding nuclei are important in the analysis of final flow observables in relativistic heavy-ion collisions. We use hydrodynamic simulations to study the amplitude correlations between different orders of event-by-event fluctuating anisotropic flow harmonics. While the general trends seen in the experimental data are qualitatively reproduced by the model, deviations in detail, in particular for peripheral collisions, point to the need for more elaborate future calculations with a hybrid approach that describes the late hadronic stage of the evolution microscopically. It is demonstrated explicitly that the observed anti-correlation between and is the consequence of approximately linear hydrodynamic response to a similar anti-correlation of the corresponding initial eccentricities and . For , the hydrodynamic correlations between and deviate from the rescaled correlations among the corresponding initial eccentricities, demonstrating nonlinear mode coupling effect in higher order flows.

    Comments:
    v2: reference and some additional discussion added. No change in conclusions
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1607.01732 [pdf]
    PRC(2016)·39 citations

Affiliations

first authorsco-authorsvia INSPIRE