Event-by-event fluctuations clusterization and entropy production in AA collisions at AGS and SPS energies

Abstract

Event-by-event (ebe) fluctuations in mean pseudorapidity values of relativistic charged particles in full phase space are studied by analyzing experimental data on [Formula: see text] collisions at 14.5A, 60A and 200A GeV/c and [Formula: see text] collisions at 200A GeV/c. The findings are compared with the prediction of A Multi-Phase Transport (AMPT) model and those obtained from the analysis of correlation free Monte-Carlo events. Fluctuations in mean pseudorapidity distributions are noted to be in excess to that expected from the statistically independent particle emission. The observed dependence of the fluctuation strength measure parameter, [Formula: see text] on the beam energy and number of participating target nucleons indicate that nucleus–nucleus collisions cannot be treated as simple superposition of multiple nucleon–nucleon interactions. Presence of clusters or jet-like phenomena in multihadron final states are searched for on ebe basis by using the concept of Jaynes Shannon entropy. The findings indicate the presence of cluster-like objects in the experimental data with their size and frequency increasing with increasing beam energy. These observations in turn suggest that the clustering or jet-like algorithm adopted in the present study may be used as a tool for triggering different classes of events.