Non-Equilibrium Phase Transition in Rapidly Expanding Matter

Non-equilibrium features of a first order phase transition from the quark-gluon plasma to a hadronic gas in relativistic heavy-ion collisions are discussed. It is demonstrated that strong collective expansion may lead to the fragmentation of the plasma phase into droplets surrounded by undersaturated hadronic gas. Subsequent hadronization of droplets will generate strong non-statistical fluctuations in the hadron rapidity distribution in individual events. The strongest fluctuations are expected in the vicinity of the phase transition threshold.