ICHEP 2016 Chicago

The curvature of the chiral pseudo-critical line from lattice QCD (15' + 5')

5 Aug 2016, 15:10

20m

Superior B

Oral Presentation Heavy Ions Heavy Ions

Speaker

Michele Mesiti (University of Pisa and INFN - Sezione di Pisa, Italy)

Description

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. In this talk I will present our recent determination of the curvature of the chiral pseudocritical line obtained by a lattice QCD computation. 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 ${\mu }_s$.

Presentation materials

mesiti_ichep2016.pdf