Mesonic correlation functions at finite temperature and density in the Nambu–Jona-Lasinio model with a Polyakov loop

Abstract

We investigate the properties of scalar and pseudoscalar mesons at finite temperature and quark chemical potential in the framework of the Nambu--Jona-Lasinio (NJL) model coupled to the Polyakov loop (PNJL model) with the aim of taking into account features of both chiral symmetry breaking and deconfinement. The mesonic correlators are obtained by solving the Schwinger-Dyson equation in the RPA approximation with the Hartree (mean field) quark propagator at finite temperature and density. In the phase of broken chiral symmetry, a narrower width for the $\ensuremath{\sigma}$ meson is obtained with respect to the NJL case; on the other hand, the pion still behaves as a Goldstone boson. When chiral symmetry is restored, the pion and $\ensuremath{\sigma}$ spectral functions tend to merge. The Mott temperature for the pion is also computed.