QCD equation of state at nonzero chemical potential: continuum results with physical quark masses at order mu^2

TL;DR

This paper calculates the QCD equation of state at small chemical potentials using lattice QCD with physical quark masses, providing key thermodynamic quantities and a parameterization for practical use.

Contribution

It presents continuum results for QCD thermodynamics at nonzero chemical potential with physical quark masses, including a parameterization for easy reconstruction of observables.

Findings

Pressure, energy density, and other thermodynamic quantities computed at small chemical potentials.

Comparison with Hadron Resonance Gas model at low temperatures.

A practical parameterization for T and mu dependence of observables.

Abstract

We determine the equation of state of QCD for nonzero chemical potentials via a Taylor expansion of the pressure. The results are obtained for N_f=2+1 flavors of quarks with physical masses, on various lattice spacings. We present results for the pressure, interaction measure, energy density, entropy density, and the speed of sound for small chemical potentials. At low temperatures we compare our results with the Hadron Resonance Gas model. We also express our observables along trajectories of constant entropy over particle number. A simple parameterization is given (the Matlab/Octave script parameterization.m, submitted to the arXiv along with the paper), which can be used to reconstruct the observables as functions of T and mu, or as functions of T and S/N.