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

Stefan Typel,David Blaschke

doi:10.3390/universe4020032

Abstract

An extension of the relativistic density functional approach to the equation of state for strongly interacting matter is suggested that generalizes a recently developed modified excluded-volume mechanism to the case of temperature- and density-dependent available-volume fractions. A parametrization 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.

Highlights

The simulation of astrophysical phenomena, such as core-collapse supernovae (CCSN) or neutron-star (NS) mergers, requires a careful modeling of strongly interacting matter in a wide range of densities and temperatures
In order to illustrate the characteristic effects of the modified EV mechanism on the equation of state (EoS), we limit the presentation to the case of symmetric matter, i.e., Yq = 0.5
The extension of the modified EV approach to a density- and temperature-dependent parametrization of the available-volume fractions as introduced in this work was successful in achieving the main goal of this study: As a generic structure of the QCD phase diagram, a first-order pseudo hadron–quark phase transition at low temperatures and a crossover for low baryon densities could be modeled that includes a critical endpoint at Tcrit = 155.5 MeV and μ B,crit = 591.8 MeV

Summary

A Phenomenological Equation of State of Strongly

Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt, Germany. GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt, Germany. Bogoliubov Laboratory for Theoretical Physics, Joint Institute of Nuclear Research, Dubna 141980, Russia. National Research Nuclear University (MEPhi), Kashirskoe shosse 31, Moscow 115409, Russia. Received: 12 December 2017; Accepted: 29 January 2018; Published: 9 February 2018

Introduction

Theoretical Model

Available-Volume Fractions and Model Parameters

Results

Conclusions