Multiplicity fluctuations due to the temperature fluctuations in high-energy nuclear collisions

TL;DR

This paper explains multiplicity fluctuations in high-energy nuclear collisions by modeling intrinsic temperature fluctuations using Tsallis statistics, linking the nonextensivity parameter to system size and fluctuation effects.

Contribution

It introduces a non-extensive statistical approach to quantify temperature fluctuations and relates the nonextensivity parameter to collision centrality and system size.

Findings

The nonextensivity parameter q increases with decreasing system size.

Temperature fluctuations are significant in finite hadronizing sources.

Tsallis statistics reduces to Boltzmann-Gibbs in the limit of no fluctuations.

Abstract

We investigate the multiplicity fluctuations observed in high-energy nuclear collisions attributing them to intrinsic fluctuations of temperature of the hadronizing system formed in such processes. To account for these fluctuations we replace the usual Boltzmann-Gibbs (BG) statistics by the non-extensive Tsallis statistics characterized by the nonextensivity parameter q, with |q-1| being a direct measure of fluctuations. In the limit of vanishing fluctuations, q --> 1 and Tsallis statistics converges to the usual BG. We evaluate the nonextensivity parameter q and its dependence on the hadronizing system size from the experimentally observed collision centrality dependence of the mean multiplicity, <N>, and its variance, Var(N). We attribute the observed system size dependence of q to the finiteness of the hadronizing source with q = 1 corresponding to an infinite, thermalized source with a fixed temperature, and with q > 1 (which is observed) corresponding to a finite source in which both the temperature and energy fluctuate.