Classical Behaviour After a Phase Transition: II. The Formation of   Classical Defects
  Classical defects (monopoles, vortices, etc.) are a characteristic consequence of many phase transitions of quantum fields. Most likely these include transitions in the early universe and such defects would be expected to be present in the universe today. We continue our analysis of the onset of classical behaviour after a second-order phase transition in quantum field theory and show how defects appear after such transitions 
R.J. Rivers, F.C. Lombardo and F.D. Mazzitelli