title: Softening of the equation of state of matter at large densities and temperatures: chiral-symmetry restoration versus quark deconfinement.
abstract: We discuss two models in which a softening of the equation of state takes place due to the appearance of new degrees of freedom. The first is a hadronic model in which the softening is due to chiral symmetry restoration. In the second model the softening is associated with the formation of clusters of quarks in the mixed phase. We show that in the first case the bulk modulus is mainly dependent on the density, while in the mixed-phase model the bulk modulus strongly depends on the temperature and it is not vanishing due to the presence of two conserved charges, the baryon and the isospin one.
authors.affiliation: Dipartimento di Fisica, Università di Ferrara and INFN, Sezione di Ferrara, 44100 Ferrara, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Bonanno
authors.forename: Alessandro
authors.initials: A
authors.lastname: Drago
authors.forename: Andrea
authors.initials: A
authors.lastname: Lavagno