Gluon density fluctuations in dilute hadrons

TL;DR

This paper investigates the fluctuations of gluon density in dilute hadrons, specifically onia, and links these fluctuations to particle multiplicity distributions in high-energy collisions, proposing universal features and analytical models.

Contribution

It introduces a systematic study of gluon density fluctuations in onia and derives analytical formulas for their universal behavior, supported by Monte Carlo simulations.

Findings

Universal features in gluon density fluctuation tails

Analytical formulas describing multiplicity distribution tails

Monte Carlo simulations confirming theoretical predictions

Abstract

Motivated by the relation existing between the gluon density in a hadron and the multiplicity of the particles measured in the final state of hadron-nucleus collisions, we study systematically the fluctuations of the gluon density in onia, which are the simplest dilute hadrons, of different sizes and at various rapidities. We argue that the small and the large-multiplicity tails of the gluon distributions present universal features, which should translate into properties of the multiplicity of the particles measured in the final state of high-energy proton-nucleus collisions, or of deep-inelastic scattering at a future electron-ion collider. We propose simple physical pictures of the rare events populating the tails of the multiplicity distribution that allow us to derive analytical formulas describing these universal behaviors, and we compare them to the results of Monte Carlo simulations.