The wave function collapse as symmetry breakdown and effect of field quantization

It is pointed out that ordinary quantum mechanics as a phenomenological theory cannot account for the wave function collapse if it is not seen within the frame work of free field quantization which is needed to understand the particle structure of matter during wave packet evolution and to explain the collapse as symmetry breakdown by detection. Deuteron photo decay and the decay of a two-fermion spin singlet state (Bohm's version of EPR) with subsequent detection of one fermion serve as examples. A projection postulate and superluminal signals are not necessary to understand what entangled states predict.