The quark gluon plasma equation of state and the expansion of the early Universe

TL;DR

This paper investigates how different equations of state for the quark-gluon plasma influence the early Universe's evolution, incorporating recent experimental, astrophysical, and lattice QCD data, including effects of baryon chemical potential.

Contribution

It compares various equations of state for the quark-gluon plasma, including MIT bag model variants and lattice QCD results, to analyze their impact on early Universe evolution.

Findings

Different equations of state significantly affect the temperature and energy density evolution.

Finite baryon chemical potential influences the early Universe dynamics.

Lattice QCD-based equations provide more accurate descriptions than simple models.

Abstract

Our knowledge of the equation of state of the quark gluon plasma has been continuously growing due to the experimental results from heavy ion collisions, due to recent astrophysical measurements and also due to the advances in lattice QCD calculations. The new findings about this state may have consequences on the time evolution of the early Universe, which can estimated by solving the Friedmann equations. The solutions of these equations give the time evolution of the energy density and also of the temperature in the beginning of the Universe. In this work we compute the time evolution of the QGP in the early Universe, comparing several equations of state, some of them based on the MIT bag model (and on its variants) and some of them based on lattice QCD calculations. Among other things, we investigate the effects of a finite baryon chemical potential in the evolution of the early Universe.