Intermittency and hidden phase transitions in multi-particle collisions

This work deals with various types of phase transitions which may occur in high-energy collisions between quarks, gluons and hadrons. It is based on the intermittency interpretations of event-per-event rapidity fluctuations described by a random cascading which could model such transitions and give necessary conditions for their existence. Using a formalism borrowed from statistical mechanics, the phase diagram of these models is derived. It yields three different phases including a newly found 'hierarchical' phase. A specific observable built from factorial bin-bin correlations is shown to be sensitive to the presence of the hierarchical phase, and gives a possible phenomenological way of studying its properties. In an appendix, we explain the replica method relevant to the statistical formulation and the solution of random cascading models in the limit of large number of steps. (orig.)