Equilibrium and nonequilibrium properties associated with the chiral phase transition at finite density in the GrossNeveu model
Abstract
We study the dynamics of the chiral phase transition at finite density in the GrossNeveu (GN) model in the leading order in the largeN approximation. The phase structure of the GN model in this approximation has the property that there is a tricritical point at a fixed temperature and chemical potential separating regions where the chiral transition is first order from that where it is second order. We consider evolutions starting in local thermal and chemical equilibrium in the massless unbroken phase for conditions pertaining to traversing a first or second order phase transition. We assume boost invariant kinematics and determine the evolution of the order parameter σ, the energy density and pressure as well as the effective temperature, chemical potential and interpolating number densities as a function of the proper time τ. We find that before the phase transition, the system behaves as if it were an ideal fluid in local thermal equilibrium with equation of state p=ɛ. After the phase transition, the system quickly reaches its true broken symmetry vacuum value for the fermion mass and for the energy density. The single particle distribution functions for fermions and antifermions go far out of equilibrium as soon as the plasma traverses the chiral phase transition. We have also determined the spatial dependence of the ``pion'' Green's function <ψ¯(x)γ_{5}ψ(x)ψ¯(0)γ_{5}ψ(0)> as a function of the proper time.
 Publication:

Physical Review D
 Pub Date:
 May 2001
 DOI:
 10.1103/PhysRevD.63.096010
 arXiv:
 arXiv:hepph/0011211
 Bibcode:
 2001PhRvD..63i6010C
 Keywords:

 11.15.Kc;
 03.70.+k;
 05.70.Ln;
 11.10.Kk;
 Classical and semiclassical techniques;
 Theory of quantized fields;
 Nonequilibrium and irreversible thermodynamics;
 Field theories in dimensions other than four;
 High Energy Physics  Phenomenology
 EPrint:
 39 pages, 23 figures