Classical Behaviour After a Phase Transition: I. Classical Order   Parameters
  We analyze the onset of classical field configurations after a phase transition. Firstly, we motivate the problem by means of a toy model in quantum mechanics. Subsequently, we consider a scalar field theory in which the system-field interacts with its environment, represented both by further scalar fields and by its own short-wavelength modes. We show that, for very rapid quenches, the order parameter can be treated classically by the time that it has achieved its ground state values (spinodal time). 
F.C. Lombardo, R.J. Rivers, and F.D. Mazzitelli