Wavelet analysis of particle density functions in nucleus–nucleus interactions

Abstract

A continuous wavelet analysis is performed for pattern recognition of the pseudorapidity density profile of singly charged particles produced in [Formula: see text]O+Ag/Br and [Formula: see text]S+Ag/Br interactions, each at an incident energy of [Formula: see text] GeV per nucleon in the laboratory system. The experiments are compared with a model prediction based on the ultra-relativistic quantum molecular dynamics (UrQMD). To eliminate the contribution coming from known source(s) of particle cluster formation like Bose–Einstein correlation (BEC), the UrQMD output is modified by “an algorithm that mimics the BEC as an after burner.” We observe that for both interactions particle clusters are found at same pseudorapidity locations at all scales. However, the cluster locations in the [Formula: see text]O+Ag/Br interaction are different from those found in the [Formula: see text]S+Ag/Br interaction. Significant differences between experiments and simulations are revealed in the wavelet pseudorapidity spectra that can be interpreted as the preferred pseudorapidity values and/or scales of the pseudorapidity interval at which clusters of particles are formed. The observed discrepancy between experiment and corresponding simulation should therefore be interpreted in terms of some kind of nontrivial dynamics of multiparticle production.