Locating the QCD critical point through contours of constant entropy density

TL;DR

This paper introduces a novel method using contours of constant entropy density to locate the QCD critical point, extrapolating from zero-density results to identify the critical temperature and chemical potential.

Contribution

It proposes a new approach to find the QCD critical point by extrapolating entropy density contours from first-principle lattice QCD results, including the critical and spinodal lines.

Findings

Critical point at T ≈ 114 MeV and μ_B ≈ 602 MeV identified

Method demonstrates potential for precise critical point determination

Encourages further lattice QCD efforts to refine results

Abstract

We propose a new method to investigate the existence and location of the conjectured high-temperature critical point of strongly interacting matter via contours of constant entropy density. By approximating these lines as a power series in the baryon chemical potential $\mu_B$, one can extrapolate them from first-principle results at zero net-baryon density, and use them to locate the QCD critical point, including the associated first-order and spinodal lines. As a proof of principle, we employ currently available continuum-extrapolated first-principle results from the Wuppertal--Budapest collaboration to find a critical point at a temperature and a baryon chemical potential of $T_c = 114.3 \pm 6.9$ MeV and $\mu_{B,c} = 602.1 \pm 62.1$ MeV, respectively. We advocate for a more precise determination of the required expansion coefficients via lattice QCD simulations as a means of pinpointing the location of the critical endpoint in the phase diagram of strongly interacting matter.