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Nuclear Theory·nucl-th

Monday·November 27, 2017

13 papers—9 primary·4 cross-listed

All13Primary9Cross-lists4
  1. 10

    [Submitted on 22 Nov 2017] (cross-list from astro-ph.HE)

    Dynamical onset of superconductivity and retention of magnetic fields in cooling neutron stars

    Wynn C.G. Ho🇬🇧 · Nils Andersson🇬🇧 · Vanessa Graber🇨🇦

    A superconductor of paired protons is thought to form in the core of neutron stars soon after their birth. Minimum energy conditions suggest magnetic flux is expelled from the superconducting region due to the Meissner effect, such that the neutron star core is largely devoid of magnetic fields for some nuclear equation of state and proton pairing models. We show via neutron star cooling simulations that the superconducting region expands faster than flux is expected to be expelled because cooling timescales are much shorter than timescales of magnetic field diffusion. Thus magnetic fields remain in the bulk of the neutron star core for at least 10^6-10^7 yr. We estimate the size of flux free regions at 10^7 yr to be <~ 100 m for a magnetic field of 10^11 G and possibly smaller for stronger field strengths. For proton pairing models that are narrow, magnetic flux may be completely expelled from a thin shell of approximately the above size after 10^5 yr. This shell may insulate lower conductivity outer layers, where magnetic fields can diffuse and decay faster, from fields maintained in the highly conducting deep core.

    Comments:
    6 pages, 5 figures; accepted for publication in Physical Review C
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Superconductivity (cond-mat.supr-con); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1711.08480 [pdf]
    PRC(2017)·18 citations
  2. 11

    [Submitted on 23 Nov 2017] (cross-list from hep-ph)

    Collectivity in small systems - Initial state vs. final state effects

    Moritz Greif🇩🇪 · Carsten Greiner🇩🇪 · Björn Schenke🇺🇸 · Sören Schlichting🇺🇸 · Zhe Xu🇨🇳

    Observations of long rang azimuthal correlations in small collision systems (p+p/A) have triggered an enormous excitement in the heavy-ion community. However, it is presently unclear to what extent the experimentally observed correlations should be attributed to initial state momentum correlations and/or the final state response to the initial state geometry. We discuss how a consistent theoretical description of the non-equilibrium dynamics is important to address both effects within a unified framework and present first results from weakly coupled non-equilibrium simulations in \cite{Greif:2017bnr} to quantify the relative importance of initial state and final state effects based on theoretical calculations.

    Comments:
    7 pages, 3 figures; Proceedings of the XLVII International Symposium on Multiparticle Dynamics, Tlaxcala City, Mexico, September 11--15, 2017; to be published in EPJ-Conferences
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1711.08557 [pdf]
    EPJ Web Conf.(2018)·1 citation
  3. 12

    [Submitted on 23 Nov 2017] (cross-list from hep-ph)

    Diffusion of conserved charges in relativistic heavy ion collisions

    Moritz Greif🇩🇪 · Jan A. Fotakis🇩🇪 · Gabriel S. Denicol🇧🇷 · Carsten Greiner🇩🇪

    In order to characterize nuclear matter under extreme conditions, we calculate all diffusion transport coefficients related to baryon, electric and strangeness charge for both a hadron resonance gas and a simplified kinetic model of the quark-gluon plasma. We demonstrate that the diffusion currents do not depend only on gradients of their corresponding charge density. Instead, we show that there exists coupling between the different charge currents, in such a way that it is possible for density gradients of a given charge to generate dissipative currents of another charge. Within this scheme, the charge diffusion coefficient is best viewed as a matrix, in which the diagonal terms correspond to the usual charge diffusion coefficients, while the off-diagonal terms describe the coupling between the different currents. In this letter, we calculate for the first time the complete diffusion matrix including the three charges listed above. We find that the baryon diffusion current is strongly affected by baryon charge gradients, but also by its coupling to gradients in strangeness. The electric charge diffusion current is found to be strongly affected by electric and strangeness gradients, whereas strangeness currents depend mostly on strange and baryon gradients.

    Comments:
    6 pages, 2 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1711.08680 [pdf]
    PRL(2018)·91 citations
  4. 13

    [Submitted on 23 Nov 2017] (cross-list from hep-ph)

    Light scalar mesons and two-kaon correlation functions

    N.N. Achasov🇷🇺 · A.V. Kiselev🇷🇺

    It is shown that the recent data on the correlation in Pb-Pb interactions agree with the data on the and reactions and support the four-quark model of the meson. It is shown that the data does not contradict the validity of the Gaussian assumption. The study of two-kaon correlations could provide more information about light scalar mesons after increasing the accuracy of the experimental and theoretical descriptions.

    Comments:
    12 pages, 3 figures. Updated version corresponding to PRD article
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1711.08777 [pdf]
    PRD(2018)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE