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Nuclear Theory·nucl-th

Friday·June 16, 2017

8 papers—3 primary·5 cross-listed

All8Primary3Cross-lists5
  1. 04

    [Submitted on 14 Jun 2017] (cross-list from astro-ph.HE)

    Muon Creation in Supernova Matter Facilitates Neutrino-driven Explosions

    R. Bollig (1,2)🇩🇪 · H.-Th. Janka (2)🇩🇪 · A. Lohs (3)🇩🇪 · G. Martinez-Pinedo (3,4)🇩🇪 · C.J. Horowitz (5)🇺🇸 · T. Melson (1) ((1) MPI Astrophysics, Garching, (2) Physik Dept., TUM, (3) GSI Darmstadt, (4) TU Darmstadt, (5) Indiana Univ., Bloomington)🇩🇪

    Muons can be created in nascent neutron stars (NSs) due to the high electron chemical potentials and the high temperatures. Because of their relatively lower abundance compared to electrons, their role has so far been ignored in numerical simulations of stellar core collapse and NS formation. However, the appearance of muons softens the NS equation of state, triggers faster NS contraction and thus leads to higher luminosities and mean energies of the emitted neutrinos. This strengthens the postshock heating by neutrinos and can facilitate explosions by the neutrino-driven mechanism.

    Comments:
    6 pages, 4 figures; one more model added upon referee request; accepted by PRL
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1706.04630 [pdf]
    PRL(2017)·215 citations
  2. 05

    [Submitted on 14 Jun 2017] (cross-list from hep-ph)

    Locating the Gribov horizon

    Fei Gao🇨🇳 · Si-Xue Qin🇨🇳 · Craig D. Roberts🇺🇸 · Jose Rodriguez-Quintero🇪🇸

    We explore whether a tree-level expression for the gluon two-point function, supposed to express effects of an horizon term introduced to eliminate the Gribov ambiguity, is consistent with the propagator obtained in simulations of lattice-regularised quantum chromodynamics (QCD). In doing so, we insist that the gluon two-point function obey constraints that ensure a minimal level of consistency with parton-like behaviour at ultraviolet momenta. In consequence, we are led to a position which supports a conjecture that the gluon mass and horizon scale are equivalent emergent mass-scales, each with a value of roughly GeV; and wherefrom it appears plausible that the dynamical generation of a running gluon mass may alone be sufficient to remove the Gribov ambiguity.

    Comments:
    7 pages, 2 figures, 2 tables
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1706.04681 [pdf]
    PRD(2018)·95 citations
  3. 06

    [Submitted on 15 Jun 2017] (cross-list from astro-ph.HE)

    New equation of states for postmerger supramassive quark stars

    Ang Li🇨🇳 · Zhen-Yu Zhu🇨🇳 · Xia Zhou🇨🇳

    Binary neutron star (NS) mergers with their subsequent fast-rotating supramassive magnetars are one attractive interpretation for at least some short gamma-ray bursts (SGRBs), based on the internal plateau commonly observed in the early X-ray afterglow. The rapid decay phase in this scenario signifies the epoch when the star collapses to a black hole after it spins down, and could effectively shed light on the underlying unclear equation of state (EoS) of dense matter. In the present work, we confront the protomagnetar masses of the internal plateau sample from representative EoS models, with the one independently from the observed galactic NS-NS binary, aiming to contribute new compact star EoSs from SGRB observations. For this purpose, we employ various EoSs covering a wide range of maximum mass for both NSs and quark stars (QSs), and in the same time satisfying the recent observational constraints of the two massive pulsars whose masses are precisely measured (around ). We first illustrate that how well the underlying EoS would reconcile with the current posterior mass distribution, is largely determined by the static maximum mass of that EoS. We then construct 3 new postmerger QS EoSs (PMQS1, PMQS2, PMQS3), respecting fully the observed distribution. We also provide easy-to-use parameterizations for both the EoSs and the corresponding maximum gravitational masses of rotating stars. In addition, we calculate the fractions of postmerger products for each EoS, and discuss potential consequences for the magnetar-powered kilonova model.

    Comments:
    12 pages, 5 figures, 3 tables, ApJ (2017) accepted
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
    arXiv:
    1706.04720 [pdf]
    ApJ(2017)·36 citations
  4. 07

    [Submitted on 15 Jun 2017] (cross-list from astro-ph.HE)

    Probing crustal structures from neutron star compactness

    Hajime Sotani · Kei Iida · Kazuhiro Oyamatsu

    With various sets of the parameters that characterize the equation of state (EOS) of nuclear matter, we systematically examine the thickness of a neutron star crust and of the pasta phases contained therein. Then, with respect to the thickness of the phase of spherical nuclei, the thickness of the cylindrical phase, and the crust thickness, we successfully derive fitting formulas that express the ratio of each thickness to the star's radius as a function of the star's compactness, the incompressibility of symmetric nuclear matter, and the density dependence of the symmetry energy. In particular, we find that the thickness of the phase of spherical nuclei has such a strong dependence on the stellar compactness as the crust thickness, but both of them show a much weaker dependence on the EOS parameters. Thus, via determination of the compactness, the thickness of the phase of spherical nuclei as well as the crust thickness can be constrained reasonably, even if the EOS parameters remain to be well-determined.

    Comments:
    accepted for publication in MNRAS
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1706.04736 [pdf]
    MNRAS(2017)·27 citations
  5. 08

    [Submitted on 15 Jun 2017] (cross-list from hep-ph)

    Transverse momentum spectra of hadrons in high energy pp and heavy ion collisions

    Kapil Saraswat🇮🇳 · Prashant Shukla🇮🇳 · Venktesh Singh🇮🇳

    We present a study of transverse momentum () spectra of unidentified charged particles in pp collisions at RHIC and LHC energies from = 62.4 GeV to 13 TeV using Tsallis/Hagedorn function. The power law of Tsallis/Hagedorn form gives excellent description of the hadron spectra in range from 0.2 to 300 GeV/. The power index of the distributions is found to follow a function of the type with asymptotic value . The parameter governing the soft bulk contribution to the spectra remains almost same over wide range of collision energies. We also provide a Tsallis/Hagedorn fit to the spectra of hadrons in pPb and different centralities of PbPb collisions at = 5.02 TeV. The data/fit shows deviations from the Tsallis distribution which become more pronounced as the system size increases. We suggest simple modifications in the Tsallis/Hagedorn power law function and show that the above deviations can be attributed to the transverse flow in low region and to the in-medium energy loss in high region.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1706.04860 [pdf]
    J.Phys.Comm.(2018)·32 citations

Affiliations

first authorsco-authorsvia INSPIRE