**The curvature of the chiral pseudo-critical line from lattice QCD**

*C. Bonati, M. D'Elia, M. Mesiti, M. Mariti, F. Negro, F. Sanfilippo*

in 38th International Conference on High Energy Physics

Contribution: pdf

**Abstract**

The study of the temperature - baryon chemical potential $T-\mu_B$

phase diagram of strongly interacting matter is being performed both

experimentally and by theoretical means. The comparison between the

experimental chemical freeze-out line and the crossover line,

corresponding to chiral symmetry restoration, is one of the main

issues. At present it is not possible to perform lattice

simulations at real $\mu_B$ because of the sign problem. In order to

circumvent this issue, we make use of analytic continuation from an

imaginary chemical potential: this approach makes it possible to

obtain reliable predictions for small real $\mu_B$. By using a

state-of-the-art discretization, we study the phase diagram of

strongly interacting matter at the physical point for purely imaginary

baryon chemical potential and zero strange quark chemical potential

$\mu_s$. We locate the pseudocritical line by computing two observables

related to chiral symmetry, namely the chiral condensate and the

chiral susceptibility. We then perform a continuum limit extrapolation

with $N_t=$6,8,10 and 12 lattices, obtaining our final estimate for

the curvature of the pseudocritical line $\kappa = 0.0135(20)$. Our

study includes a thorough analysis of the systematics involved in the

definition of $T_c(\mu_B)$, and of the effect of a nonzero $\mu_s$.