The realistic QCD equation of state in relativistic heavy-ion collisions and the early Universe

TL;DR

This paper applies a realistic QCD equation of state to model the early Universe's thermodynamic evolution, revealing a crossover transition that moderately dampens inhomogeneities, contrasting with ideal-gas models.

Contribution

It introduces the use of a realistic QCD equation of state in cosmological modeling, providing more accurate insights into early Universe thermodynamics.

Findings

The realistic equation of state indicates a crossover transition.

Inhomogeneities are moderately damped during the crossover.

Results differ from those using ideal-gas equations of state.

Abstract

The realistic equation of state of strongly interacting matter, that has been successfully applied in the recent hydrodynamic studies of hadron production in relativistic heavy-ion collisions at RHIC, is used in the Friedmann equation to determine the precise time evolution of thermodynamic parameters in the early Universe. A comparison with the results obtained with simple ideal-gas equations of state is made. The realistic equation of state describes a crossover rather than the first-order phase transition between the quark-gluon plasma and hadronic matter. Our numerical calculations show that small inhomogeneities of strongly interacting matter in the early Universe are moderately damped during such crossover.