QCD thermodynamics at zero and non-zero density

TL;DR

This paper investigates the thermodynamics of QCD at zero and non-zero density using lattice simulations with improved staggered fermions, analyzing cut-off effects and the behavior of fluctuations and correlations across different temperatures.

Contribution

It provides new lattice results for the QCD equation of state at various lattice spacings and explores the Taylor expansion method for non-zero chemical potential.

Findings

Correlations match resonance gas model below T_c

Start to agree with free gas predictions above 1.5 T_c

Lattice cut-off effects are systematically analyzed

Abstract

We present results on the QCD equation of state, obtained with two different improved dynamical staggered fermion actions and almost physical quark masses. Lattice cut-off effects are discussed in detail as results for three different lattice spacings are available now, i.e. results have been obtained on lattices with temporal extent of $N_\tau=4,6$ and 8. Furthermore we discuss the Taylor expansion approach to non-zero baryon chemical potential by means of an expansion of the pressure. We use the expansion coefficients to calculate various fluctuations and correlations among hadronic charges. We find that the correlations reproduce the qualitative behavior of the resonance gas model below $T_c$ and start to agree with the free gas predictions for $T\gsim 1.5T_c$.