# Rapidity Decorrelation from Hydrodynamic Fluctuations and Initial Fluctuations

## TL;DR

This paper investigates the causes of rapidity decorrelation in high-energy heavy-ion collisions by using 3D relativistic hydrodynamics simulations, highlighting the roles of hydrodynamic and initial fluctuations.

## Contribution

It provides a comprehensive analysis of rapidity decorrelation by combining hydrodynamic fluctuations and initial longitudinal fluctuations in a realistic simulation framework.

## Key findings

- Both hydrodynamic and initial fluctuations contribute to factorization breaking.
- Hydrodynamic fluctuations significantly impact rapidity decorrelation.
- Initial longitudinal fluctuations are also crucial in understanding the phenomenon.

## Abstract

Rapidity decorrelation in high energy heavy-ion collisions is one of the hot topics in understanding longitudinal dynamics of the quark gluon plasma (QGP). In this study we employ an integrated dynamical model with full three dimensional relativistic hydrodynamics and perform event-by-event numerical simulations of Pb+Pb collisions at the LHC energy. We analyze factorization ratios to understand rapidity decorrelation from hydrodynamic fluctuations and initial longitudinal fluctuations. We show that factorization breaking happens due to both hydrodynamic fluctuations and initial longitudinal fluctuations. We conclude hydrodynamic fluctuations and initial longitudinal fluctuations are both important in understanding rapidity decorrelation.