# Multiplicity fluctuations near the QCD critical point

## TL;DR

This paper develops a framework to calculate statistical moments of particle multiplicities in heavy-ion collisions, accounting for experimental limitations and background effects, to better identify signals of the QCD critical point.

## Contribution

It introduces a comprehensive method for evaluating multiplicity moments considering correlations, resonance decays, acceptance, and efficiency, aiding the search for the QCD critical point.

## Key findings

- Framework accounts for critical and spurious correlations.
- Includes effects of resonance decay and detector efficiency.
- Focuses on second-order moments with straightforward extension to higher orders.

## Abstract

Statistical moments of particle multiplicities in heavy-ion collision experiments are an important probe in the exploration of the phase diagram of strongly interacting matter and, particularly, in the search for the QCD critical end point. In order to appropriately interpret experimental measures of these moments, however, it is necessary to understand the role of experimental limitations, as well as background contributions, providing expectations on how critical behavior should be affected by them. We here present a framework for calculating moments of particle multiplicities in the presence of correlations of both critical and spurious origins. We also include effects from resonance decay and a limited acceptance window, as well as detector efficiency. Although we focus on second-order moments, for simplicity, an extension to higher-order moments is straightforward.