Neutrino emissivities and bulk viscosity in neutral two-flavor quark matter

TL;DR

This paper investigates the thermodynamic and transport properties of the iso-CSL phase in two-flavor superconducting quark matter, demonstrating its potential to replace phenomenological models in neutron star cooling simulations.

Contribution

It provides a self-consistent calculation of neutrino emissivities and bulk viscosities in the iso-CSL phase, offering a microscopic foundation for modeling quark matter in compact stars.

Findings

Iso-CSL phase satisfies cooling and rotational constraints of compact stars.

Results support replacing phenomenological models with iso-CSL in star evolution simulations.

Demonstrates density-dependent changes in quark properties affect transport coefficients.

Abstract

We study thermodynamic and transport properties for the isotropic color-spin-locking (iso-CSL) phase of two-flavor superconducting quark matter under compact star constraints within a NJL-type chiral quark model. Chiral symmetry breaking and the phase transition to superconducting quark matter leads to a density dependent change of quark masses, chemical potentials and diquark gap. A self-consistent treatment of these physical quantities influences on the microscopic calculations of transport properties. We present results for the iso-CSL direct URCA emissivities and bulk viscosities, which fulfill the constraints on quark matter derived from cooling and rotational evolution of compact stars. We compare our results with the phenomenologically successful, but yet heuristic 2SC+X phase. We show that the microscopically founded iso-CSL phase can replace the purely phenomenological 2SC+X phase in modern simulations of the cooling evolution for compact stars with color superconducting quark matter interior.