Equation of State for physical quark masses

TL;DR

This paper computes the QCD equation of state at physical quark masses using lattice simulations, providing insights into the transition region and comparing with previous heavier mass results and a resonance gas model.

Contribution

It presents the first calculation of the QCD equation of state at physical quark masses with an improved staggered fermion action on N_tau=8 lattices.

Findings

Transition region shifts by about 5 MeV to smaller temperatures at physical quark masses.

Results agree with previous calculations at larger quark masses and resonance gas models.

Analysis of deconfining and chiral transition indicators such as Polyakov loop and chiral condensate.

Abstract

We calculate the QCD equation of state for temperatures corresponding to the transition region with physical mass values for two degenerate light quark flavors and a strange quark using an improved staggered fermion action (p4-action) on lattices with temporal extent N_tau=8. We compare our results with previous calculations performed at twice larger values of the light quark masses as well as with results obtained from a resonance gas model calculation. We also discuss the deconfining and chiral aspects of the QCD transition in terms of renormalized Polyakov loop, strangeness fluctuations and subtracted chiral condensate. We show that compared to the calculations performed at twice larger value of the light quark mass the transition region shifts by about 5 MeV toward smaller temperatures