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

Understand

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.