Thermodynamics with 3 and 2+1 Flavors of Improved Staggered Quarks

TL;DR

This paper investigates the phase diagram of finite temperature QCD using improved staggered quarks with different flavor configurations, demonstrating reduced lattice artifacts and flavor symmetry breaking, and providing preliminary results across various lattice sizes.

Contribution

It introduces an improved staggered quark action that reduces lattice artifacts and flavor symmetry breaking, enhancing the study of QCD thermodynamics.

Findings

Improved staggered quarks lead to better thermodynamic properties.

Flavor symmetry breaking is substantially decreased.

All pions are lighter than the lightest kaon at transition temperature.

Abstract

We present preliminary results from exploring the phase diagram of finite temperature QCD with three degenerate flavors and with two light flavors and the mass of the third held approximately at the strange quark mass. We use an order $\alpha_s^2 a^2, a^4$ Symanzik improved gauge action and an order $\alpha_s a^2, a^4$ improved staggered quark action. The improved staggered action leads to a dispersion relation with diminished lattice artifacts, and hence better thermodynamic properties. It decreases the flavor symmetry breaking of staggered quarks substantially, and we estimate that at the transition temperature for an $N_t=8$ to $N_t=10$ lattice {\em all} pions will be lighter than the lightest kaon. Preliminary results on lattices with $N_t=4$, 6 and 8 are presented.