The Equation of State for QCD with 2+1 Flavors of Quarks
  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 $m_{ud} =0.1m_s$ 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. 
C. Bernard, T. Burch, C. DeTar, Steven Gottlieb, U. M. Heller, J. E.   Hetrick, L. Levkova, F. Maresca, D. B. Renner, R. Sug...