Equation of state of a hot-and-dense quark gluon plasma: lattice simulations at real $\mu_B$ vs. extrapolations

TL;DR

This paper compares different methods for calculating the equation of state of hot, dense quark-gluon plasma at finite baryon density, using lattice simulations and reweighting techniques to evaluate their accuracy across the RHIC BES range.

Contribution

It provides a direct comparison of novel approximation schemes with lattice results at finite chemical potential, highlighting their validity limits.

Findings

Reweighting techniques yield results free from overlap problems.

Comparison shows the range of validity for various approximation schemes.

Results cover the entire RHIC BES baryochemical potential range up to μ_B/T=3.

Abstract

The equation of state of the quark gluon plasma is a key ingredient of heavy ion phenomenology. In addition to the traditional Taylor method, several novel approximation schemes have been proposed with the aim of calculating it at finite baryon density. In order to gain a pragmatic understanding of the limits of these schemes, we compare them to direct results at $\mu_B>0$, using reweighting techniques free from an overlap problem. We use 2stout improved staggered fermions with 8 time-slices and cover the entire RHIC BES range in the baryochemical potential, up to $\mu_B/T=3$.