We argue that the parton distributions measured in heavy ion collisions depend on the trigger for the centrality of the collisions as a result of coherent effects specific for the collisions of energetic composite particles. Percolation phase transitions in central heavy ion collisions are predicted and methods to form and to investigate such baryon rich matter are suggested.

• Received 8 June 1993

DOI:https://doi.org/10.1103/PhysRevD.48.R1894