Phase diagrams in the hadron-Polyakov-Nambu-Jona-Lasinio model

The two-equation of state model is used to describe the hadron-quark phase transition in dense-hot matter formed in heavy-ion collisions. The nonlinear Walecka model is used to describe the hadronic phase. For the quark phase, the Nambu-Jona-Lasinio (NJL) model coupled to Polyakov-loop fields is used to include both the chiral and (de)confinement dynamics. The phase diagrams are derived from the Gibbs conditions and compared with the results obtained in the hadron-NJL model without confinement. As in the hadron-NJL case a first order transition is observed, but with a critical end point at much higher temperatures, a consequence of the confinement mechanism that reduces the degrees of freedom of the quark matter in proximity to the phase transition. Particular attention is devoted to the phase transition in isospin asymmetric matter. Interesting isospin effects are found at high baryon density and reduced temperatures, which are in fact also common to other quark models, like the MIT bag model and the NJL model. Some possible observational signals are suggested to probe in heavy-ion collision experiments at intermediate energies.