Lattice determination of the critical point of QCD at finite T and μ

TL;DR

The paper tackles locating the QCD critical endpoint in the $\mu$–$T$ plane using ab initio lattice QCD with dynamical $n_f=2+1$ staggered quarks. It introduces a finite-size scaling analysis of Lee-Yang zeros in the complex $\beta$ plane combined with a reweighting scheme to map the phase boundary at finite $\mu$ on $L_t=4$ lattices. The main findings place the endpoint at $T_E=160 \pm 3.5$ MeV and $\mu_E=725 \pm 35$ MeV, with $T_c=172 \pm 3$ MeV at $\mu=0$, providing a nonperturbative prediction for the critical point and demonstrating a viable lattice strategy for finite-$\mu$ studies, while highlighting the need for chiral and continuum extrapolations and larger volumes. The work establishes a framework for ab initio QCD phase diagram exploration, relevant for interpreting heavy-ion experiments and guiding future lattice efforts toward physical quark masses and finer lattices.

Abstract

Based on universal arguments it is believed that there is a critical point (E) in QCD on the temperature (T) versus chemical potential (μ) plane, which is of extreme importance for heavy-ion experiments. Using finite size scaling and a recently proposed lattice method to study QCD at finite μwe determine the location of E in QCD with n_f=2+1 dynamical staggered quarks with semi-realistic masses on $L_t=4$ lattices. Our result is T_E=160 \pm 3.5 MeV and μ_E= 725 \pm 35 MeV. For the critical temperature at μ=0 we obtained T_c=172 \pm 3 MeV.