# Bose-Einstein correlations in perturbative QCD: $v_n$ dependence on multiplicity

## TL;DR

This paper investigates how Bose-Einstein correlations influence azimuthal angle correlations and flow coefficients in high-energy collisions, highlighting the role of multiplicity and soft gluon suppression, with a proposed model for ion-ion interactions.

## Contribution

It introduces a detailed analysis of Bose-Einstein correlations' dependence on multiplicity and proposes a KLN-type model for ion-ion collision centrality effects.

## Key findings

- Bose-Einstein correlations dominate azimuthal correlations in high-multiplicity events.
- Soft gluon emission leads to Sudakov suppression, affecting jet production.
- In hadron-hadron collisions, correlations depend strongly on multiplicity, unlike in heavy-ion collisions.

## Abstract

In this paper we study the dependence of Bose-Einstein correlations on the multiplicity of an event. We found that events with large multiplicity, stem from the production of several parton showers, while the additional production of small multiplicity in the central rapidity region (central diffraction), gives a negligible contribution due to emission of soft gluons, that leads to the Sudakov suppression of the exclusive production of two gluon jets. Hence, the Bose-Einstein correlation is the main source of the azimuthal angle correlations which generates $v_n$ with odd and even $n$. We found, that without this suppression, the measurement of an event with given multipilicity, yields $v_{n,n} < 0$ for odd $n$. It appears that in hadron-nucleus and nucleus-nucleus collisions, the Bose-Einstein correlations do not depend on multiplicity, while for hadron-hadron scattering, such dependence can be considerable. We proposed a simple Kharzeev-Levin-Nardi (KLN) type model, to describe the dependence of azimuthal angle correlations on the centrality of the event, in ion-ion collisions.