Time evolution of collective motion of quantum meson fields

The dynamical process of chiral phase transition is investigated in the O(4) linear sigma model. The time evolution of chiral condensate and quantum meson modes is described self-consistently by means of the functional Schroedinger picture with a time-dependent Gaussian wave functional. It is shown that the solutions corresponding to quantum rotations in isospin space are obtained and a remarkable effects arise because of the coupling between the mean field, i.e., chiral condensate, and its quantum fluctuations. The damping time of collective isospin rotation and emitted number of pions in the relaxation process are also evaluated. Further, in the case of rolling down of chiral condensate in so-called quench scenario in chiral phase transition, the mechanism of amplification of quantum pion modes are discussed. (author)