# Influence of Backside Energy Leakages from Hadronic Calorimeters on Fluctuation Measures in Relativistic Heavy-Ion Collisions

## TL;DR

This paper investigates how energy leakages in hadronic calorimeters affect fluctuation measurements in heavy-ion collision experiments, emphasizing the impact of centrality selection efficiency on different system sizes.

## Contribution

It introduces a model to quantify the influence of backside energy leakages on fluctuation measures across various colliding systems in heavy-ion experiments.

## Key findings

- Light systems are highly sensitive to centrality selection inefficiencies.
- Heavy systems show minimal impact from energy leakage effects.
- Modeling indicates significant effects on multiplicity fluctuations in small systems.

## Abstract

The phase diagram of the strongly interacting matter is the main research subject for different current and future experiments in high-energy physics. System size and energy scan programs aim to find a possible critical point. One of such programs was accomplished by the fixed-target NA61/SHINE experiment in 2018. It includes six beam energies and six colliding systems: p + p, Be + Be, Ar + Sc, Xe + La, Pb + Pb and p + Pb. In this study, we discuss how the efficiency of centrality selection by forward spectators influences multiplicity and fluctuation measures and how this influence depends on the size of colliding systems. We use SHIELD and EPOS Monte-Carlo (MC) generators along with the wounded nucleon model, introduce a probability to lose a forward spectator and spectator energy loss. We show that for light colliding systems such as Be or Li even a small inefficiency in centrality selection has a dramatic impact on multiplicity scaled variance. Conversely, heavy systems such as Ar + Sc are much less prone to the effect.