arXiv subjects

Germán Lugones

Publications and source records attributed to Germán Lugones.

22 records · Page 2Linked to original sources

arXiv2014

Neutrino diffusive transport in hot quark matter: a detailed analysis

We perform an extensive analysis of neutrino diffusion in quark matter within the MIT bag model at arbitrary temperature and degeneracy. We examine in detail the contribution of each of the relevant weak interaction processes to the total neutrino opacity and evaluate the effect of the strange quark mass, the bag constant, and the QCD perturbative corrections to the MIT bag model. We also investigate the anisotropic contribution to the neutrino distribution function in scatterings, the mean energy transfer and the mean scattering angle. The density and temperature dependence of the diffusion coefficients $D_n$ that govern the cooling and deleptonization of a compact star is shown in detail. Finally, our numerical results for the neutrino mean free paths are compared against known analytic approximations. We conclude that neutrino scattering constitutes a significant portion of the total neutrino opacity in leptonized quark matter and neutrino-quark scattering is, in general, very similar to neutrino-electron scattering with respect to both mean energy transfer per scattering and mean scattering angle.

astro-ph.SR↗

arXiv2013

Quark deconfinement in protoneutron star cores: effect of color superconductivity within the MIT bag model

We analyze the effect of color superconductivity in the transition from hot hadron matter to quark matter in the presence of a gas of trapped electron neutrinos. To describe strongly interacting matter we adopt a two-phase picture in which the hadronic phase is described by means of a non-linear Walecka model and just deconfined matter through the MIT bag model including color superconductivity. We impose flavor conservation during the transition in such a way that just deconfined quark matter is transitorily out of equilibrium with respect to weak interactions. Our results show that color superconductivity facilitates the transition for temperatures below $T_c$. This effect may be strong if the superconducting gap is large enough. As in previous work we find that trapped neutrinos increase the critical density for deconfinement; however, if the just deconfined phase is color superconducting this effect is weaker than if deconfined matter is unpaired. We also explore the effect of different parametrizations of the hadronic equation of state (GM1 and NL3) and the effect of hyperons in the hadronic phase. We compare our results with those previously obtained employing the Nambu-Jona-Lasinio model in the description of just deconfined matter and show that they are in excellent agreement if the bag constant $B$ is properly chosen.

astro-ph.HE↗

arXiv2013

Deconfinement transition in protoneutron star cores: Analysis within the MIT Bag model

We analyze the effect of color superconductivity in the transition from hot hadron matter to quark matter in the presence of a gas of trapped electron neutrinos. We adopt a two-phase picture in which the hadronic phase is described trough a nonlinear Walecka model and just deconfined matter through the MIT bag model including color superconductivity. We compare the present results with those obtained within the NJL model.

nucl-th↗

arXiv2013

Implications of PSR J1614-2230 for NJL hybrid star

The recent determination of the mass of the pulsar PSR J1614-2230 with $1.97 \pm 0.04 M_\odot$ by \cite{Demorest}, renewed the discussions about the possibility of exotic matter being present at the core of neutron stars. Since the description of matter at densities beyond nuclear saturation is model dependent, several works have explored different aspects of the fact that the maximum neutron star mass implied by any equation of state (EoS) must exceed the mass of PSR J1614-2230. In this article we present an extensive study of hybrid star masses using several parametrizations of a relativistic mean-field hadronic EoS together with a typical three-flavor NJL model with scalar, vector and 't Hooft interactions as realized.

astro-ph.HE↗