Scaling properties of multiplicity fluctuations in heavy ion collisions simulated by AMPT model

TL;DR

This study investigates multiplicity fluctuations in heavy ion collisions using the AMPT model, revealing self-similar fractal behavior and increased fluctuations at higher transverse momentum, with implications for understanding phase transition dynamics.

Contribution

It provides a detailed analysis of fluctuation scaling and intermittency indices in heavy ion collisions, highlighting differences from phase transition models.

Findings

Fluctuations exhibit power-law scaling indicating self-similarity.

Intermittency index ${ u}$ exceeds Ginzburg-Landau phase transition value.

Fluctuations increase rapidly with transverse momentum.

Abstract

Three-dimensional, as well as one- and two-dimensional, studies of multiplicity fluctuation are performed using AMPT model to generate central Au-Au collision events at ${\sqrt s_{NN}}= 200$ GeV. Two- and three-dimensional normalized factorial moments in rapidity, transverse momentum and azimuthal angle are found to exhibit power-low scaling when partitioning with the same number of bins in each direction, indicating that the fluctuation are isotropic, i.e. the fractality is self-similar in multiparticle production of central Au-Au collisions. Further, we measured the parameter ${\nu}$ which it characterizes the intermittency indices derived in particular analysis. It is found that our model result ${\nu_{y{\phi}p_t}}= 1.86{\pm}0.07$ is larger than ${\nu} = 1.304$,which is the value of Ginzburg-Landau type of phase transition. We also explored the intermittent or fluctuational dependence on the transverse momentum. The result shows that the intermittency or fluctuation increase rapidly with the increasing of transverse momentum.