QCD equation of state with 2+1 flavors of improved staggered quarks

Abstract

We report results for the interaction measure, pressure and energy density for nonzero temperature QCD with 2+1 flavors of improved staggered quarks. In our simulations we use a Symanzik improved gauge action and the Asqtad $O(a^2)$ improved staggered quark action for lattices with temporal extent $N_t=4$ and 6. The heavy quark mass $m_s$ is fixed at approximately the physical strange quark mass and the two degenerate light quarks have masses $m_{ud}\approx 0.1m_s$ or $0.2m_s$. The calculation of the thermodynamic observables employs the integral method where energy density and pressure are obtained by integration over the interaction measure.

25 pages, 11 figures, 5 tables; One more figure added. Eq. 11 changed. Some text changes