Emergence of long wavelength pion oscillations following a rapid QCD phase transition

To model the dynamics of the chiral order parameter in a far from equilibrium QCD phase transition, we consider quenching in the O(4) linear sigma model. We summarize arguments and numerical evidence which show that in the period immediately following the quench arbitrarily long wavelength modes of the pion field are amplified. This results in large regions of coherent pion oscillations, and could lead to dramatic phenomenological consequences in ultra-relativistic heavy ion collisions. My talk was a description of work done with Frank Wilczek. In these proceedings, I sketch our central results, emphasizing several points that were raised in discussions at the conference.