The QCD Equation of State to $\mathcal{O}(\mu_B^4)$ from Lattice QCD

TL;DR

This paper computes the QCD equation of state up to fourth order in baryon chemical potential using lattice QCD, providing insights relevant for heavy-ion collision experiments at various energies.

Contribution

It presents the first lattice QCD calculation of the QCD equation of state to $ ext{O}(\mu_B^4)$, extending previous work to include higher-order corrections.

Findings

Second-order corrections suffice for RHIC beam energy scan range.

Higher-order corrections needed for lower beam energies (~20 GeV).

Results inform the modeling of QCD matter in heavy-ion collisions.

Abstract

We present first results from a first-principles calculation of the QCD equation of state to $\mathcal{O}(\mu_B^4)$, where $\mu_B$ is the baryon chemical potential. We find that second-order corrections are sufficient for a large part of the freeze-out temperature and baryon chemical potential range achieved by the RHIC beam energy scan. Nevertheless, higher-order corrections are necessary to extend the validity of the equation of state down to beam energies $s^{1/2}_{NN}\sim 20$ GeV.