To bin or not to bin: does binning in multiplicity reliably suppress unwanted volume fluctuations?

TL;DR

This paper investigates the effectiveness of the Centrality Bin Width Correction (CBWC) method in accurately measuring proton number fluctuations in nucleus-nucleus collisions, highlighting conditions for its success and failure.

Contribution

The study provides an analytical model to evaluate when CBWC reliably suppresses volume fluctuations and identifies scenarios where it may give misleading results.

Findings

CBWC effectively removes volume fluctuations under certain conditions.

The model shows cases where CBWC fails to correct for impact parameter fluctuations.

Analytical insights guide proper application of CBWC in experimental analyses.

Abstract

In this study, we examine the effect of the so-called Centrality Bin Width Correction (CBWC) on the measurement of (net-)proton number cumulants in nucleus-nucleus collisions. We present an analytically tractable model, which includes correlations between multiplicity and proton number similar to those generated by the decay of baryon resonances. Within this model, we analyze the circumstances under which the CBWC method correctly removes the undesired effects of volume or impact parameter fluctuations. Additionally, we explore situations where the method fails and produces misleading results.