# Event-by-Event Fluctuations Clusterization and Entropy Production in AA Collisions at AGS and SPS Energies

## TL;DR

This study investigates event-by-event fluctuations and clustering phenomena in relativistic heavy-ion collisions at various energies, revealing excess fluctuations and cluster-like structures that suggest complex underlying dynamics beyond simple nucleon-nucleon superposition.

## Contribution

It introduces an analysis of pseudorapidity fluctuations and clustering using Shannon entropy, demonstrating energy-dependent clustering and non-trivial fluctuation behavior in AA collisions.

## Key findings

- Excess pseudorapidity fluctuations beyond independent emission expectations.
- Detection of cluster-like objects increasing with beam energy.
- Fluctuation measure $$ varies with energy and participant nucleons.

## Abstract

Event-by-event (ebe) fluctuations in mean pseudorapidity values of relativistic charged particles in full phase space is studied by analysing experimental data on $^{16}O-AgBr$ collisions at 14.5A, 60A, and 200A GeV/c and $^{32}S-AgBr$ collisions at 200A GeV/c. The findings are compared with the prediction of A Multi-Phase Transport(\amm) model and those obtained from the analysis of correlation free Monte-Carlo events. Fluctuations in mean pseudorapidity distributions are noticed to be in excess to that expected from the statistically independent particle emission. The observed dependence of the fluctuation strength measure parameter,$\phi$ on the beam energy and number of participating target nucleons indicate that nucleus-nucleus collisions can not 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.