# Finite size of hardons and HBT interferometry for hydrodynamic sources

## TL;DR

This paper investigates how the finite size of hadrons influences HBT interferometry measurements in heavy-ion collisions, revealing that volume effects suppress correlation functions especially at high transverse momenta and for small sources.

## Contribution

It introduces a detailed analysis of the excluded volume effect on HBT correlations across various source sizes and momenta, highlighting its significance in interpreting experimental data.

## Key findings

- Volume effects are more pronounced in narrow space-time sources.
- Correlation functions are suppressed at high transverse momenta due to volume effects.
- Incoherence parameters decrease with volume effects, especially in small collision systems.

## Abstract

Hadrons formed in heavy-ion collisions are not point-like objects, they cannot occupy too close space-time points. When the two bosons are too close to each other, their constituents start to mix and they cannot be considered as bosons subjected to Bose-Einstein statistics, this effect is called excluded volume effect. We study the volume effect on HBT for the sources with various sizes. The effect on HBT was shown in out, side and long directions, and it is more obvious for the source with a narrow space-time distribution. The correlation functions for high transverse momenta are more suppressed by the volume effect. Hence the incoherence parameter may be more suppressed by the volume effect for high transverse momenta in small collision systems.