Cosmological QCD phase transition in steady non-equilibrium dissipative Ho\v{r}ava-Lifshitz early universe

TL;DR

This paper investigates the QCD phase transition in the early universe within a non-equilibrium, viscous cosmological model based on Hořava-Lifshitz gravity, analyzing how viscosity and gravity parameters influence early universe dynamics.

Contribution

It introduces a novel analysis of the QCD phase transition considering viscous effects in Hořava-Lifshitz cosmology with non-detailed balance, incorporating both Eckart and Israel-Stewart fluid models.

Findings

Viscosity significantly affects temperature and scale factor evolution.

Hořava-Lifshitz gravity parameters influence early universe expansion.

Viscous effects modify the deceleration parameter during phase transition.

Abstract

We study the phase transition from quark-gluon plasma to hadrons in the early universe in the context of non-equilibrium thermodynamics. According to the standard model of cosmology, a phase transition associated with chiral symmetry breaking after the electro-weak transition has occurred when the universe was about $1-10\mu s$ old. We focus attention on such a phase transition in the presence of a viscous relativistic cosmological background fluid in the framework of non-detailed balance Ho\v{r}ava-Lifshitz cosmology within an effective model of QCD. We consider a flat Friedmann-Robertson-Walker Universe filled with a non-causal and causal bulk viscous cosmological fluid respectively and investigate the effects of the running coupling constants of Ho\v{r}ava-Lifshitz gravity, $\lambda$, on the evolution of the physical quantities relevant to a description of the early universe, namely, the temperature $T$, scale factor $a$, deceleration parameter $q$ and dimensionless ratio of the bulk viscosity coefficient to entropy density $\frac{\xi}{s}$. We assume that the bulk viscosity cosmological background fluid obeys the evolution equation of the steady truncated (Eckart) and full version of the Israel-Stewart fluid, respectively.