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Nuclear Theory·nucl-th

Wednesday·June 17, 2020

13 papers—4 primary·9 cross-listed

All13Primary4Cross-lists9
  1. 01

    [Submitted on 15 Jun 2020]

    Stellar electron capture rates based on finite temperature relativistic quasiparticle random-phase approximation

    A. Ravlic🇭🇷 · E. Yuksel · Y. F. Niu🇨🇳 · G. Colo🇮🇹 · E. Khan🇫🇷 · N. Paar🇭🇷

    The electron capture process plays an important role in the evolution of the core collapse of a massive star that precedes the supernova explosion. In this study, the electron capture on nuclei in stellar environment is described in the relativistic energy density functional framework, including both the finite temperature and nuclear pairing effects. Relevant nuclear transitions are calculated using the finite temperature proton-neutron quasiparticle random phase approximation with the density-dependent meson-exchange effective interaction DD-ME2. The pairing and temperature effects are investigated in the Gamow-Teller transition strength as well as the electron capture cross sections and rates for Ti and Fe in stellar environment. It is found that the pairing correlations establish an additional unblocking mechanism similar to the finite temperature effects, that can allow otherwise blocked single-particle transitions. Inclusion of pairing correlations at finite temperature can significantly alter the electron capture cross sections, even up to a factor of two for Ti, while for the same nucleus electron capture rates can increase by more than one order of magnitude. We conclude that for the complete description of electron capture on nuclei both pairing and temperature effects must be taken into account.

    Comments:
    16 pages, 11 figures, submitted to Physical Review C
    Subjects:
    Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
    arXiv:
    2006.08803 [pdf]
    PRC(2020)·23 citations
  2. 02

    [Submitted on 15 Jun 2020]

    Analytical attractor for Bjorken expansion

    Jean-Paul Blaizot🇫🇷 · Li Yan🇨🇳

    We present an analytic solution of a simple set of equations that govern the expansion of boost-invariant plasmas of massless particles. These equations describe, approximately, the early time, collisionless regime, and the transition to hydrodynamics at late time. Their mathematical structure encompasses all versions of second order hydrodynamics when applied to Bjorken flows. The analytic solution provides an explicit expression for the attractor solution that connects the collisionless regime to hydrodynamics. It also constitutes a neat example of an application of the theory of resurgence in asymptotic series.

    Comments:
    Updates with new discussion on transasymptotic matching. Version accepted for publication in PLB
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2006.08815 [pdf]
    PLB(2021)·50 citations
  3. 03

    [Submitted on 16 Jun 2020]

    Enhanced yield ratio of light nuclei in heavy ion collisions with a first-order QCD phase transition

    Kai-Jia Sun🇺🇸 · Che Ming Ko🇺🇸 · Feng Li🇨🇳 · Jun Xu🇨🇳 · Lie-Wen Chen🇨🇳

    Using a transport model that includes a first-order chiral phase transition between the partonic and the hadronic matter, we study the development of density fluctuations in the matter produced in heavy ion collisions as it undergoes the phase transition, and their time evolution in later hadronic stage of the collisions. Using the coalescence model to describe the production of deuterons and tritons from nucleons at the kinetic freeze out, we find that the yield ratio , where , , and are, respectively, the proton, deuteron, and triton numbers, is enhanced if the evolution trajectory of the produced matter in the QCD phase diagram passes through the spinodal region of a first-order chiral phase transition.

    Comments:
    12 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2006.08929 [pdf]
    EPJA(2021)·26 citations
  4. 04

    [Submitted on 14 Jun 2020]

    Impact of single string structure and multiple string interaction on strangeness production in Pb+Pb collisions at TeV

    Dai-Mei Zhou🇨🇳 · Liang Zheng🇨🇳 · Zhi-Hong Song🇨🇳 · Yu-Liang Yan🇨🇳 · Gang Chen🇨🇳 · Xiao-Mei Li🇨🇳 · Xu Cai🇨🇳 · Ben-Hao Sa🇨🇳

    We present a systematic study on the strange and multi-strange particles production in Pb+Pb collisions at TeV based on the PACIAE model simulations. Two different mechanisms, namely the single string structure variations and multiple string interactions, are implemented in the simulations. These modifications give rise to an enhancement of the string tension value involved in the Lund string fragmentation framework and generate more strange particles in the hadronic final state. By comparing the simulation results with the ALICE experimental data, it turns out that the inclusion of the variable effective string tension in the PACIAE model is capable to reach an improved agreement between theory and experiment on the strangeness production in Pb+Pb collisions.

    Comments:
    6 pages, 4 figures. arXiv admin note: text overlap with arXiv:1806.11390
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2006.09212 [pdf]
    PRC(2020)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE