QUANTUM EVOLUTION OF THE DISORIENTED CHIRAL CONDENSATES

We study the dynamics of the chiral phase transition expected during t he expansion of the quark-gluon plasma produced in a high energy hadro n or heavy ion collision, using the O(4) linear sigma model in the mea n field approximation. Imposing boost invariant initial conditions at an initial proper time tau(0) and starting from an approximate equilib rium configuration, we investigate the possibility of formation of dis oriented chiral condensate during the expansion. In order to create la rge domains of disoriented chiral condensates low-momentum instabiliti es have to last for long enough periods of time. Our simulations show no instabilities for an initial thermal configuration. For some of the out-of-equilibrium initial states studied, the fluctuation in the num ber of particles with low transverse momenta become large at late prop er times.