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Nuclear Theory·nucl-th

Monday·January 11, 2016

9 papers—3 primary·6 cross-listed

All9Primary3Cross-lists6
  1. 01

    Equation of state of a quark-Polyakov loop-meson mixture in the PNJL model at finite temperature

    Juan M. Torres-Rincon🇫🇷 · Joerg Aichelin🇫🇷

    Recent consensus on the equation of state at vanishing chemical potential from different lattice-QCD groups has spoiled the previous agreement with the outcome from the mean-field Polyakov-Nambu-Jona-Lasinio model. In this letter we review the thermodynamics of the PNJL model introducing two important aspects needed to describe the pressure computed in the lattice QCD. First, we consider the thermodynamics of the model beyond the mean-field approach to include pseudoscalar and scalar mesonic-like fluctuations into the grand-canonical potential. This accounts for the hadronic pressure of the system below the critical temperature. On the other hand we also implement the back reaction of quarks into the Polyakov-loop effective potential bringing a reduction of the pressure above from the Stefan-Boltzmann limit. We get a good agreement with lattice-QCD data at low and moderate temperatures, opening the door to a straightforward extension to finite chemical potential.

    nucl-thhep-ph13 citations
  2. 02

    Low density nuclear matter with quantum molecular dynamics : The role of the symmetry energy

    Rana Nandi · Stefan Schramm

    We study the effect of isospin-dependent nuclear forces on the pasta phase in the inner crust of neutron stars. To this end we model the crust within the framework of quantum molecular dynamics (QMD). For maximizing the numerical performance, a newly developed code has been implemented on GPU processors. As a first application of the crust studies we investigate the dependence of the particular pasta phases on the isospin dependence of the interaction, including non-linear terms in this sector of the interactions. Our results indicate that in contrast to earlier studies the phase diagram of the pasta phase is not very sensitive to isospin effects. We show that the extraction of the isospin parameters like asymmetry energy and slope from numerical data is affected by higher-order terms in the asymmetry dependence of the energies per particle. Furthermore, a rapid transition from the pasta to a homogeneous phase is observed even for proton-to-neutron ratios typical for a supernova environment.

    nucl-thastro-ph.SRPRC(2016)·32 citations
  3. 03

    Conventional and Unconventional Pairing and Condensates in Dilute Nuclear Matter

    John W Clark · Armen Sedrakian · Martin Stein · Xu-Guang Huang · Victor A Khodel · Vasily R Shaginyan · Mikhail V Zverev

    This contribution will survey recent progress toward an understanding of diverse pairing phenomena in dilute nuclear matter at small and moderate isospin asymmetry, with results of potential relevance to supernova envelopes and proto-neutron stars. Application of {\it ab initio} many-body techniques has revealed a rich array of temperature-density phase diagrams, indexed by isospin asymmetry, which feature both conventional and unconventional superfluid phases. At low density there exist a homogeneous translationally invariant BCS phase, a homogeneous LOFF phase violating translational invariance, and an inhomogeneous translationally invariant phase-separated BCS phase. The transition from the BCS to the BEC phases is characterized in terms of the evolution, from weak to strong coupling, of the pairing gap, condensate wave function, and quasiparticle occupation numbers and spectra. Additionally, a schematic formal analysis of pairing in neutron matter at low to moderate densities is presented that establishes conditions for the emergence of both conventional and unconventional pairing solutions and encompasses the possibility of dineutron formation.

    nucl-thJ.Phys.Conf.Ser.(2016)·8 citations

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first authorsco-authorsvia INSPIRE