Amplification of Pionic Instabilities in High-Energy Collisions?

Considering a variety of dynamical scenarios within the linear σ model, we examine the conditions for pionic modes to be amplified as the chiral field relaxes towards the normal vacuum following the transient restoration of approximate chiral symmetry in a high-energy collision. While Bjorken-type longitudinal expansions appear to be insufficient for amplification for occur, analogous expansions in two or three dimensions may enhance the low-energy power spectrum by up to an order of magnitude.