Main Image


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


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 $\mu_s$.