Phenomenological Equation of State of Strongly Interacting Matter with First-Order Phase Transitions and Critical Points

Abstract

An extension of the relativistic density functional approach to the equation of state for strongly interacting matter is suggested which generalizes a recently developed modified excluded-volume mechanism to the case of temperature and density dependent available-volume fractions. A parametrisation of this dependence is presented for which at low temperatures and suprasaturation densities a first-order phase transition is obtained. It changes for increasing temperatures to a crossover transition via a critical endpoint. This provides a benchmark case for studies of the role of such a point in hydrodynamic simulations of ultrarelativistic heavy-ion collisions. The approach is thermodynamically consistent and extendable to finite isospin asymmetries that are relevant for simulations of neutron stars, their mergers and core-collapse supernova explosions.