Entropy production in the early-cosmology pionic phase

TL;DR

This paper investigates entropy production in the early universe's pion gas phase, focusing on how temperature inhomogeneities relax and contribute to entropy, highlighting a relatively unexplored cosmological epoch.

Contribution

It provides an analysis of entropy production due to thermal inhomogeneities in the pion gas after the quark-gluon plasma phase, emphasizing its significance in early-universe cosmology.

Findings

Pions carried significant entropy in the early universe.

Thermal conductivity influences entropy production during inhomogeneity relaxation.

The study highlights the importance of the pion phase in early-universe entropy dynamics.

Abstract

We point out that in the early universe, for temperatures in the approximate interval 175-80 MeV (after the quark-gluon plasma), pions carried a large share of the entropy and supported the largest inhomogeneities. Thus, we examine the production of entropy in a pion gas, particularizing to inhomogeneities of the temperature, for which we benefit from the known thermal conductivity. We finally put that entropy produced in relaxing such thermal inhomogeneities in the broad context of this relatively unexplored phase of early-universe cosmology.