Speaker
Description
Centrality fluctuations is one of the main uncertainties for interpreting the centrality dependence of many experimental observables. The centrality fluctuation is constrained by selection based on particle multiplicity in a reference subevent, and contributes to observables measured in another subevent. Due to the asymmetry between forward- and backward-going participating nucleons, the number of sources for particle production is a function of $\eta$ even in a single event, which leads to centrality decorrelation between different rapidities. Using a Glauber-based independent source model, we study the influence of centrality decorrelations on multi-particle cumulants. In mid-central collisions, a general relation is established between the multiplicity fluctuation and resulting centrality resolution in given subevent. In ultra-central collisions, where distribution of particle production sources is strongly distorted, we find these cumulants exhibit different behavior, due to observable-dependent non-Gaussianity in the underlying distributions. Furthermore, we investigate the influence centrality fluctuations in HIJING and UrQMD models. This study can be considered as a first step towards detailed understanding of the longitudinal dynamics for particle production in heavy-ion collisions.
