# 3-D Glasma initial state from small-x evolution

## TL;DR

This paper develops an ab-initio method incorporating small-x evolution into the IP-Glasma model to compute the initial state in heavy-ion collisions, revealing how rapidity-dependent gluon distributions influence observable correlations.

## Contribution

It extends the IP-Glasma model by integrating JIMWLK rapidity evolution, enabling detailed event-by-event predictions of longitudinal gluon distributions and correlations.

## Key findings

- Small-x evolution affects rapidity correlations in gluon multiplicities.
- The model's predictions align with experimental observations.
- Longitudinal structure of the initial state is significantly influenced by small-x dynamics.

## Abstract

We present an ab-initio approach to compute the longitudinal dependence of the initial state in heavy-ion collisions by including small-x evolution of the nuclear gluon distributions. Extending the IP-Glasma model by including JIMWLK rapidity evolution, we compute event-by-event rapidity distributions of produced gluons and the early time energy momentum tensor as a function of space-time rapidity and transverse coordinates. We show how the effects of small-x evolution manifest themselves in longitudinal (rapidity) correlations of event-by-event multiplicities and transverse geometry and compare our results to various phenomenological models and experimental observations.