# Volume fluctuation and multiplicity correlation on higher-order cumulants

## TL;DR

This study evaluates the effectiveness of volume fluctuation correction methods on higher-order cumulants in heavy-ion collisions, revealing limitations of current techniques and emphasizing the need for method comparison in experiments.

## Contribution

It systematically compares volume fluctuation correction and centrality bin width correction methods using toy and UrQMD models for higher-order cumulants.

## Key findings

- VFC works well in toy model with independent particle production
- VFC does not perform well in UrQMD model
- Both VFC and CBWC have limitations and should be compared in experiments

## Abstract

Initial volume fluctuation (VF) arising from the participant fluctuation would be the background which should be subtracted experimentally from the measured higher-order cumulants. We study the validity of the Volume Fluctuation Correction (VFC) on higher-order net-proton cumulants by using simple toy model and UrQMD model in Au+Au collisions at \sqrt s_{NN} = 200 GeV for various centrality definitions. The results are compared to the conventional data driven method called Centrality Bin Width Correction (CBWC). We find VFC works well in toy model assuming independent particle production (IPP), but does not seem to work well in UrQMD model. It is also found that cumulants are strongly affected by the multiplicity correlation effect as well as the centrality resolution effect. These results show that neither VFC nor CBWC are perfect method. Thus, both methods should be compared in the real experiment.