Equilibrium and nonequilibrium properties associated with the chiral phasetransition at finite density in the Gross-Neveu model - art. no. 096010

We study the dynamics of the chiral phase transition at finite density in t he Gross-Neveu (GN) model in the leading order in the large-hi approximatio n. The phase structure of the GN model in this approximation has the proper ty that there is a tricritical point at a fixed temperature and chemical po tential separating regions where the chiral transition is first order from that where it is second order. We consider evolutions starting in local the rmal and chemical equilibrium in the massless unbroken phase for conditions pertaining to traversing a first or second order phase transition. We assu me boost invariant kinematics and determine the evolution of the order para meter sigma, the energy density and pressure as well as the effective tempe rature, chemical potential and interpolating number densities as a function of the proper time tau. We find that before the phase transition, the syst em behaves as if it were an ideal fluid in local thermal equilibrium with e quation of state p = epsilon. After the phase transition, the system quickl y reaches its true broken symmetry vacuum value for the fermion mass and fo r the energy density. The single particle distribution functions for fermio ns and antifermions go far out of equilibrium as soon as the plasma travers es the chiral phase transition. We have also determined the spatial depende nce of the "pion" Green's function [<(<psi>)over bar>(x) gamma (5)psi (x)<( <psi>)over bar>(0) gamma (5)psi (0)] as a function of the proper time.