Neutrino Emission From Direct Urca Processes in Pion Condensed Quark Matter

TL;DR

This paper investigates how pion condensation in dense quark matter affects neutrino emission, revealing enhanced cooling rates in compact stars due to gapless modes, especially with significant quark mass differences.

Contribution

It provides the first detailed analysis of neutrino emission from pion condensed quark matter, highlighting the impact of gapless modes on emissivity and stellar cooling.

Findings

Neutrino emission is dominated by gapless modes in pion condensed quark matter.

Enhanced emissivity leads to faster cooling in compact stars with pion condensation.

Mass differences between u- and d-quarks significantly increase neutrino emission rates.

Abstract

We study neutrino emission from direct Urca processes in pion condensed quark matter. In compact stars with high baryon density, the emission is dominated by the gapless modes of the pion condensation which leads to an enhanced emissivity. While for massless quarks the enhancement is not remarkable, the emissivity is significantly larger and the cooling of the condensed matter is considerably faster than that in normal quark matter when the mass difference between $u$- and $d$-quarks is sizable.