Curvature of the chiral pseudo-critical line in QCD

TL;DR

This study uses lattice QCD simulations at imaginary chemical potentials to accurately determine the curvature of the pseudo-critical line, providing insights into the phase transition behavior of strong interactions.

Contribution

It presents a new determination of the curvature of the QCD pseudo-critical line using improved lattice techniques and compares different methods and systematic effects.

Findings

The curvature is estimated as κ=0.013(2)(1).

Results are consistent across different observables and lattice spacings.

Analysis of strange quark chemical potential effects and systematic uncertainties.

Abstract

We determine the curvature of the pseudo-critical line of strong interactions by means of numerical simulations at imaginary chemical potentials. We consider $N_f=2+1$ stout improved staggered fermions with physical quark masses and the tree level Symanzik gauge action, and explore two different sets of lattice spacings, corresponding to temporal extensions $N_t = 6$ and $N_t = 8$. Both the renormalized chiral condensate and the renormalized chiral susceptibility are used to locate the transition. The determinations obtained from the two quantities are in good agreement, a preliminary continuum extrapolation yields $\kappa = 0.013(2)(1)$. We also investigate the impact of a non-zero strange quark chemical potential and compare our results to previous determinations in the literature, discussing the possible sources of systematic errors affecting the various procedures.