Bulk viscosity of spin-one color superconducting strange quark matter

TL;DR

This paper calculates the bulk viscosity of spin-one color-superconducting strange quark matter, revealing significant increases compared to normal matter, with implications for neutron star dynamics, especially in different superconducting phases.

Contribution

It provides the first detailed analysis of bulk viscosity in spin-one color-superconducting phases, including semi-leptonic processes and phase-dependent enhancements.

Findings

Bulk viscosity increases up to 29 times in certain phases.

Semi-leptonic processes have a limited impact in spin-one phases.

Spin-one color superconductivity generally enhances bulk viscosity across temperatures.

Abstract

The bulk viscosity in spin-one color-superconducting strange quark matter is calculated by taking into account the interplay between the nonleptonic and semi-leptonic week processes. In agreement with previous studies, it is found that the inclusion of the semi-leptonic processes may result in non-negligible corrections to the bulk viscosity in a narrow window of temperatures. The effect is generally more pronounced for pulsars with longer periods. Compared to the normal phase, however, this effect due to the semi-leptonic processes is less pronounced in spin-one color superconductors. Assuming that the critical temperature of the phase transition is much larger than 40 keV, the main effect of spin-one color superconductivity in a wide range of temperatures is an overall increase of the bulk viscosity with respect to the normal phase. The corresponding enhancement factor reaches up to about 9 in the polar and A-phases, about 25 in the planar phase and about 29 in the CSL phase. This factor is determined by the suppression of the nonleptonic rate in color-superconducting matter and, therefore, may be even larger if all quark quasiparticles happen to be gapped.