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Nuclear Theory·nucl-th

Friday·October 20, 2017

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 05

    Fermionic Light Dark Matter particles and the New Physics of Neutron Stars

    M. Cermeño🇪🇸 · M. Ángeles Pérez-García🇪🇸 · Joseph Silk🇫🇷

    Dark Matter constitutes most of the matter in the presently accepted cosmological model for our Universe. The extreme conditions of ordinary baryonic matter, namely high density and compactness, in Neutron Stars make these objects suitable to gravitationally accrete such a massive component provided interaction strength between both, luminous and dark sectors, at current experimental level of sensitivity. We consider several different DM phenomenological models from the myriad of those presently allowed. In this contribution we review astrophysical aspects of interest in the interplay of ordinary matter and a fermionic light Dark Matter component. We focus in the interior nuclear medium in the core and external layers, i.e. the crust, discussing the impact of a novel dark sector in relevant stellar quantities for (heat) energy transport such as thermal conductivity or emissivities.

    ↳ astro-ph.HEhep-phnucl-thPubl.Astron.Soc.Austral.(2017)·21 citations
  2. 06

    Investigating thermalization of a strongly interacting non-Abelian plasma

    L. Bellantuono🇵🇱 · P. Colangelo🇮🇹 · F. De Fazio🇮🇹 · F. Giannuzzi🇮🇹 · S. Nicotri🇮🇹

    Using gauge/gravity duality methods, we study the relaxation towards equilibrium of strongly interacting non-Abelian matter. We adopt boundary sourcing to drive the system out-of-equilibrium, and analyze the equilibration process through local probes (energy density and pressures) and nonlocal probes (lengths of the geodesics between two boundary points and extremal surfaces having a Wilson loop as contour on the boundary). We also investigate the real-time dissociation of the heavy quarkonium in the out-of-equilibrium plasma. Systematic comparison with the results of a geometry dual to viscous hydrodynamics sheds light on the thermalization process.

    ↳ hep-phhep-thnucl-thPoS(2017)·0 citations
  3. 07

    Coupled kinetic equations for quarks and gluons in the relaxation time approximation

    Wojciech Florkowski🇵🇱 · Ewa Maksymiuk🇵🇱 · Radoslaw Ryblewski🇵🇱

    Kinetic equations for quarks and gluons are solved numerically in the relaxation time approximation for the case of one-dimensional boost-invariant geometry. Quarks are massive and described by the Fermi-Dirac statistics, while gluons are massless and obey Bose-Einstein statistics. The conservation laws for the baryon number, energy, and momentum lead to two Landau matching conditions which specify the coupling between the quark and gluon sectors and determine the proper-time dependence of the effective temperature and baryon chemical potential of the system. The numerical results illustrate how a non-equlibrium mixture of quarks and gluons approaches hydrodynamic regime described by the Navier-Stokes equations with appropriate forms of the kinetic coefficients. The shear viscosity of a mixture is the sum of the shear viscosities of quark and gluon components, while the bulk viscosity is given by the formula known for a gas of quarks, however, with the thermodynamic variables characterising the mixture. Thus, we find that massless gluons contribute in a non-trivial way to the bulk viscosity of a mixture, provided quarks are massive. We further observe the hydrodynamization effect which takes place earlier in the shear sector than in the bulk one. The numerical studies of the ratio of the longitudinal and transverse pressures show, to a good approximation, that it depends on the ratio of the relaxation and proper times only. This behaviour is connected with the existence of an attractor solution for conformal systems.

    ↳ hep-phnucl-thPRC(2018)·46 citations

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first authorsco-authorsvia INSPIRE