The QCD EoS from simulations on BlueGene L Supercomputers at LLNL and NYBlue

TL;DR

This paper presents high-precision lattice QCD simulations of the equation of state at zero chemical potential, providing results that are crucial for interpreting heavy-ion collision experiments at RHIC and LHC.

Contribution

The study offers the first high-statistics lattice QCD results for the EoS using improved staggered quarks on large lattices, with estimates close to the continuum limit and a refined crossover temperature range.

Findings

Consistent results between two improved staggered quark actions.

Trace anomaly estimates are within 20% of the continuum value.

Estimated crossover temperature is 185-195 MeV.

Abstract

We present results for the QCD Equation of State (EoS) obtained using simulations of lattice QCD at zero chemical potential. Our high statistics results compare improved asqtad and p4fat3 staggered quarks on lattices with a temporal extent N_tau = 6 and 8 and light quark masses approximately one fifth and one tenth the strange quark mass. We find that the two actions give consistent results and estimate that the trace anomaly (epsilon - 3p)/T^4 obtained on N_tau = 8 lattices represents the continuum value to better than 20% uncertainty over the temperature range 140-700 MeV. The precision in the estimates of energy density and pressure are better, therefore, we conclude that lattice estimates of the energy density and pressure should be used in the phenomenological analysis of RHIC and LHC data. We also find a consistent picture of the crossover temperature from all observables studied, with the best estimated range to be 185-195 MeV. These calculations are being carried out on the IBM BlueGene/L supercomputer at Lawrence Livermore National Laboratory and at the New York Center for Computational Science (NYBlue).