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Nuclear Theory·nucl-th

Wednesday·August 19, 2015

10 papers—3 primary·7 cross-listed

All10Primary3Cross-lists7
  1. 01

    [Submitted on 18 Aug 2015]

    Present status of coupled-channels calculations for heavy-ion subbarrier fusion reactions

    K. Hagino · J.M. Yao

    The coupled-channels method has been a standard tool in analyzing heavy-ion fusion reactions at energies around the Coulomb barrier. We investigate three simplifications usually adopted in the coupled-channels calculations. These are i) the exclusion of non-collective excitations, ii) the assumption of coordinate independent coupling strengths, and iii) the harmonic oscillator approximation for multi-phonon excitations. In connection to the last point, we propose a novel microscopic method based on the beyond-mean-field approach in order to take into account the anharmonic effects of collective vibrations.

    Comments:
    10 pages, 4 figures. A talk given at the 12th International Conference on Nucleus-Nucleus Collisions (NN2015), June 21-26, Catania, Italy
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1508.04222 [pdf]
    EPJ Web Conf.(2016)·2 citations
  2. 02

    [Submitted on 18 Aug 2015]

    Inhomogeneous chiral symmetry breaking in dense neutron-star matter

    Michael Buballa🇩🇪 · Stefano Carignano🇩🇪

    An increasing number of model results suggests that chiral symmetry is broken inhomogeneously in a certain window at intermediate densities in the QCD phase diagram. This could have significant effects on the properties of compact stars, possibly leading to new astrophysical signatures. In this contribution we discuss this idea by reviewing recent results on inhomogeneous chiral symmetry breaking under an astrophysics-oriented perspective. After introducing two commonly studied spatial modulations of the chiral condensate, the chiral density wave and the real kink crystal, we focus on their properties and their effect on the equation of state of quark matter. We also describe how these crystalline phases are affected by different elements which are required for a realistic description of a compact star, such as charge neutrality, the presence of magnetic fields, vector interactions and the interplay with color-superconductivity. Finally, we discuss possible signatures of inhomogeneous chiral symmetry breaking in the core of compact stars, considering the cases of mass-radius relations and neutrino emissivity explicitly.

    Comments:
    Invited contribution to the EPJA Topical Issue "Exotic Matter in Neutron Stars". v2: extended discussion on strange quarks, updated mass-radius section, other small changes; matches published version. 16 pages, 14 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1508.04361 [pdf]
    EPJA(2016)·50 citations
  3. 03

    [Submitted on 18 Aug 2015]

    Deviations of the Energy-Momentum Tensor from Equilibrium in the Initial State for Hydrodynamics from Transport Approaches

    Dmytro Oliinychenko🇩🇪 · Hannah Petersen🇩🇪

    Many hybrid models of heavy ion collisions construct the initial state for hydrodynamics from transport models. Hydrodynamics requires that the energy-momentum tensor and four-currents do not deviate considerably from the equilibrium ideal-fluid form, but the ones constructed from transport do not necessarily possess this property. In this work we investigate the space-time picture of deviations from equilibrium in Au+Au collisions using a coarse-grained transport approach. The collision energy is varied in the range GeV. The sensitivity of deviations from equilibrium to collision centrality, and other parameters such as the switching criterion, the amount of statistics used to construct the initial state, and the smearing parameter is investigated. For low statistics deviations of from equilibrium are large and dominated by the effect of finite sampling. For large statistics the pressure anisotropy plays the most significant role, while the off-diagonal components of are small in a large volume during the whole evolution. For all considered energies and centralities the pressure anisotropy exhibits a similar feature: there is a narrow interval of time, when it rapidly drops in a considerable volume. This allows us to introduce an "isotropization time," which is found to decrease with energy and slightly increase with centrality. The isotropization times are larger than times typically used for initializing hydrodynamics.

    Comments:
    12 pages, 12 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1508.04378 [pdf]
    PRC(2016)·57 citations

Affiliations

first authorsco-authorsvia INSPIRE