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Nuclear Theory·nucl-th

Thursday·April 30, 2015

8 papers—4 primary·4 cross-listed

All8Primary4Cross-lists4
  1. 05

    [Submitted on 28 Apr 2015] (cross-list from astro-ph.SR)

    Neutrino-driven explosion of a 20 solar-mass star in three dimensions enabled by strange-quark contributions to neutrino-nucleon scattering

    Tobias Melson (1,2)🇩🇪 · Hans-Thomas Janka (1)🇩🇪 · Robert Bollig (1,2)🇩🇪 · Florian Hanke (1,2)🇩🇪 · Andreas Marek (3)🇩🇪 · Bernhard Mueller (4) ((1) MPI Astrophysics, Garching, (2) Physik Dept., TUM, Garching, (3) RZG Garching, (4) Monash University, Victoria)🇦🇺

    Interactions with neutrons and protons play a crucial role for the neutrino opacity of matter in the supernova core. Their current implementation in many simulation codes, however, is rather schematic and ignores not only modifications for the correlated nuclear medium of the nascent neutron star, but also free-space corrections from nucleon recoil, weak magnetism or strange quarks, which can easily add up to changes of several 10% for neutrino energies in the spectral peak. In the Garching supernova simulations with the Prometheus-Vertex code, such sophistications have been included for a long time except for the strange-quark contributions to the nucleon spin, which affect neutral-current neutrino scattering. We demonstrate on the basis of a 20 M_sun progenitor star that a moderate strangeness-dependent contribution of g_a^s = -0.2 to the axial-vector coupling constant g_a = 1.26 can turn an unsuccessful three-dimensional (3D) model into a successful explosion. Such a modification is in the direction of current experimental results and reduces the neutral-current scattering opacity of neutrons, which dominate in the medium around and above the neutrinosphere. This leads to increased luminosities and mean energies of all neutrino species and strengthens the neutrino-energy deposition in the heating layer. Higher nonradial kinetic energy in the gain layer signals enhanced buoyancy activity that enables the onset of the explosion at ~300 ms after bounce, in contrast to the model with vanishing strangeness contributions to neutrino-nucleon scattering. Our results demonstrate the close proximity to explosion of the previously published, unsuccessful 3D models of the Garching group.

    Comments:
    8 pages, 5 figures; minor revisions, accepted by ApJL
    Subjects:
    Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1504.07631 [pdf]
    ApJL(2015)·229 citations
  2. 06

    [Submitted on 29 Apr 2015] (cross-list from hep-ph)

    Temperature dependence of meson screening masses; a comparison of effective model with lattice QCD

    Masahiro Ishii🇯🇵 · Takahiro Sasaki🇯🇵 · Kouji Kashiwa🇯🇵 · Hiroaki Kouno🇯🇵 · Masanobu Yahiro🇯🇵

    Temperature dependence of pion and sigma-meson screening masses is evaluated by the Polyakov-loop extended Nambu--Jona-Lasinio model with the entanglement vertex (EPNJL model). We propose a practical way of calculating meson screening masses in the NJL-type effective models. The method based on the Pauli-Villars regularization solves the well-known difficulty that the evaluation of screening masses is not easy in the NJL-type effective models. The method is applied to analyze temperature dependence of pion screening masses calculated with state-of-the-art lattice simulations with success in reproducing the lattice QCD results. We predict the temperature dependence of pole mass by using EPNJL model.

    Comments:
    7 pages, 3 figures, Presented at The 32nd International Symposium on Lattice Field Theory, Lattice2014
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1504.07706 [pdf]
    PoS(2014)·0 citations
  3. 07

    [Submitted on 29 Apr 2015] (cross-list from hep-ph)

    The (3770) resonance and its production in

    J. Haidenbauer🇩🇪 · G. Krein🇧🇷

    The production of a meson-pair in antiproton-proton () annihilation close to the production threshold is investigated, with special emphasis on the role played by the (3770) resonance. The study is performed in a meson-baryon model where the elementary charm production process is described by baryon exchange. Effects of the interactions in the initial and final states are taken into account rigorously, where the latter involves also those due to the (3770). The predictions for the production cross section are in the range of 30 -- 250 nb, the contribution from the (3770) resonance itself amounts to roughly 20 -- 80 nb.

    Comments:
    6 pages, 6 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1504.07909 [pdf]
    PRD(2015)·13 citations
  4. 08

    [Submitted on 29 Apr 2015] (cross-list from hep-ph)

    Higher order anisotropies in hydrodynamics

    M. Csanad🇭🇺 · A. Szabo🇭🇺 · S. Lokos🇭🇺 · A. Bagoly🇭🇺

    In the last years it has been revealed that if measuring relative to higher order event planes , higher order flow coefficients for can be measured. It also turned out that Bose-Einstein (HBT) correlation radii also show 3rd order oscillations if measured versus the third order event plane . In this paper we investigate how these observables can be described via analytic hydro solutions and hydro parameterizations. We also investigate the time evolution of asymmetry coefficients and the mixing of velocity field asymmetries and density asymmetries.

    Comments:
    8 pages, 6 figures. Presented at the X Workshop on Particle Correlations and Femtoscopy (WPCF 2014), Gyongyos, Hungary
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1504.07932 [pdf]
    JCEGI 4(4) pp 46-52 (2016)·0 citations

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first authorsco-authorsvia INSPIRE