Volume Fluctuation and Autocorrelation Effects in the Moment Analysis of Net-proton Multiplicity Distributions in Heavy-Ion Collisions

TL;DR

This paper investigates how volume fluctuations and autocorrelation effects influence the analysis of net-proton multiplicity moments in heavy-ion collisions, proposing methods to correct artifacts and accurately estimate statistical errors.

Contribution

It identifies measurement artifacts affecting moment analysis and introduces correction methods to improve the reliability of physical interpretations in heavy-ion collision studies.

Findings

Volume fluctuation effects can bias moment measurements.

Autocorrelation effects impact the accuracy of multiplicity moments.

Proposed correction methods improve the extraction of physical signals.

Abstract

Moments (Variance ($\sigma^2$), Skewness($S$), Kurtosis($\kappa$)) of multiplicity distributions of conserved quantities, such as net-baryon,net-charge and net-strangeness, are predicted to be sensitive to the correlation length of the system and connected to the thermodynamic susceptibilities computed in Lattice QCD and Hadron Resonance Gas (HRG) model. In this paper, we present several measurement artifacts that could lead to volume fluctuation and auto-correlation effects in the moment analysis of net-proton multiplicity distributions in heavy-ion collisions using the UrQMD model. We discuss methods to overcome these artifacts so that the extracted moments could be used to obtain physical conclusions. In addition we present methods to properly estimate the statistical errors in moment analysis.