Kinetic description of vacuum particle production in collisions of ultrarelativistic nuclei

The dynamics of partons that emerge as the result of quantum tunneling in a spatially uniform time-dependent field is studied under conditions prevale nt in ultrarelativistic heavy-ion collisions. A self-consistent set of coup led equations that consists of the renormalized Maxwell equation and the Vl asov kinetic equation that involves a source and which is derived on a dyna mical basis is solved numerically. The time dependence of the distributions of internal fields and currents for bosons and fermions is investigated wi thin this back-reaction mechanism, and their momentum spectra are construct ed. Clear evidence that oscillations in the time dependence of parton distr ibutions in phase-space cells are of a stochastic character is obtained, an d a significant irregularity in the momentum distribution on large time sca les is found. If the influence of the back reaction is disregarded, these e ffects disappear completely, the oscillations becoming regular. A possible thermalization scenario for such a quasiparticle plasma is considered in th e relaxation-time approximation. A locally equilibrium state is described w ithin the two-component thermodynamics of particles and antiparticles. The possibility of introducing temperature under conditions of a strong vacuum polarization is discussed. (C) 2001 MAIK "Nauka/Interperiodica".