The QCD equation of state with dynamical quarks

TL;DR

This paper presents a detailed lattice QCD study of the equation of state with 2+1 flavors, using improved actions and finer lattices to approach the continuum limit, providing results for thermodynamic quantities across a wide temperature range.

Contribution

It extends previous lattice QCD calculations by employing finer lattices, physical quark masses, and improved actions to more accurately determine the QCD equation of state.

Findings

Thermodynamic quantities are computed across 100-1000 MeV.

Results approach the continuum limit with lattices up to N_t=12.

Comparison with hotQCD data shows consistency and differences.

Abstract

The present paper concludes our investigation on the QCD equation of state with 2+1 staggered flavors and one-link stout improvement. We extend our previous study [JHEP 0601:089 (2006)] by choosing even finer lattices. Lattices with $N_t=6,8$ and 10 are used, and the continuum limit is approached by checking the results at $N_t=12$. A Symanzik improved gauge and a stout-link improved staggered fermion action is utilized. We use physical quark masses, that is, for the lightest staggered pions and kaons we fix the $m_\pi/f_K$ and $m_K/f_K$ ratios to their experimental values. The pressure, the interaction measure, the energy and entropy density and the speed of sound are presented as functions of the temperature in the range $100 ...1000 \textmd{MeV}$. We give estimates for the pion mass dependence and for the contribution of the charm quark. We compare our data to the equation of state obtained by the "hotQCD" collaboration.