The curvature of the pseudo-critical line in the QCD phase diagram from mesonic lattice correlation functions

TL;DR

This study calculates the curvature of the pseudo-critical line in the QCD phase diagram using mesonic lattice correlation functions, providing a novel approach that aligns with previous lattice QCD results.

Contribution

First calculation of the curvature coefficient using mesonic correlation functions in lattice QCD, offering an alternative method to thermodynamic observables.

Findings

Results are consistent with previous lattice QCD studies.

Demonstrates the viability of using mesonic correlators to study QCD phase transitions.

Provides a new approach to determine the QCD phase diagram curvature.

Abstract

In the QCD phase diagram, the dependence of the pseudo-critical temperature, $T_{\rm{pc}}$, on the baryon chemical potential, $\mu_B$, is of fundamental interest. The variation of $T_{\rm{pc}}$ with $\mu_B$ is normally captured by $\kappa$, the coefficient of the leading (quadratic) term of the polynomial expansion of $T_{\rm{pc}}$ with $\mu_B$. In this work, we present the first calculation of $\kappa$ using hadronic quantities. Simulating $N_f=2+1$ flavours of Wilson fermions on {\sc Fastsum} ensembles, we calculate the ${\cal O}(\mu_B^2)$ correction to mesonic correlation functions. By demanding degeneracy in the vector and axial-vector channels we obtain $T_{\rm{pc}}(\mu_B)$ and hence $\kappa$. While lacking a continuum extrapolation and being away from the physical point, our results are consistent with previous works using thermodynamic observables (renormalised chiral condensate, strange quark number susceptibility) from lattice QCD simulations with staggered fermions.