Nonlinear evolution of the momentum dependent condensates in strong interaction: The "pseudoscalar laser"

We discuss the relaxation of the scalar and pseudoscalar condensates after a rapid quench from an initial state with fluctuations. If we include not only the zero mode but also higher modes of the condensates in the classical evolution, we observe parametric amplification of those ''hard'' modes. Thus, they couple nonlinearly to the "soft" modes. As a consequence, domains of a coherent pi field emerge long after the initial spinodal decomposition. The momentum-space distribution of pions emerging from the decay of that momentum-dependent condensate is discussed.