Local multiplicity fluctuations in Pb$-$Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 TeV with ALICE at the LHC

TL;DR

This paper analyzes local multiplicity fluctuations in Pb-Pb collisions at 2.76 TeV using factorial moments to investigate critical behavior and phase transition signals, comparing experimental data with models.

Contribution

It presents the first detailed factorial moment analysis of multiplicity fluctuations in Pb-Pb collisions at LHC energies, exploring intermittency and phase transition indicators.

Findings

Power-law growth of factorial moments suggests self-similar fluctuations.

Scaling exponent varies with $p_{T}$ bin width, indicating critical behavior.

Comparison with models shows consistency with experimental intermittency patterns.

Abstract

Local multiplicity fluctuations are an useful tool to understand the dynamics of the particle production and the phase-space changes from quarks to hadrons in ultrarelativistic heavy-ion collisions. The study of scaling behavior of multiplicity fluctuations in geometrical configurations in multiparticle production can be performed using the factorial moments and recognized in terms of a phenomenon referred to as intermittency. In this contribution, the analysis of the factorial moment is presented for the multiplicity distributions of charged particles produced in Pb$-$Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 TeV, recorded with the ALICE detector at the LHC. The normalized factorial moments (NFM), $F_{q}$ of the spatial configurations of charged particles in two-dimensional angular ($\eta,\varphi$) phase space are calculated. For a system with dynamic fluctuations due to the characteristic critical behavior near the phase transition, $F_{q}$ exhibits power-law growth with increasing bin number or decreasing bin size which indicates self-similar fluctuations. Relating the $q^{\rm{th}}$ order NFM ($F_{q}$) to the second-order NFM ($F_{2}$), the value of the scaling exponent ($\nu$) is extracted, which indicates the order of the phase transition within the framework of Ginzburg-Landau theory. The dependence of scaling exponent on the $p_{\rm{T}}$ bin width will be presented. The measurements are also compared with the corresponding results from the AMPT model and a Toy Monte Carlo (MC) simulation.