# New paradigm for fluctuations in heavy-ion collisions

## TL;DR

This paper introduces a new approach focusing on QCD interaction-driven fluctuations in heavy-ion collisions, offering improved descriptions of flow ratios and energy evolution compared to traditional models.

## Contribution

It presents a QCD-based formalism for initial state fluctuations in heavy-ion collisions, validated against RHIC and LHC data, improving upon Glauber-inspired models.

## Key findings

- Better description of the centrality dependence of flow ratios.
- Natural explanation for elliptic flow fluctuation evolution.
- Enhanced agreement with experimental data.

## Abstract

Since their discovery, fluctuations in the initial state of heavy-ion collisions have been understood as originating mostly from the random positions of nucleons within the colliding nuclei. We consider an alternative approach where all the focus is on fluctuations generated by QCD interactions, that we evaluate at leading logarithmic accuracy in the color glass condensate effective theory. We validate our approach using BNL Relativistic Heavy Ion Collider (RHIC) and CERN Large Hadron Collider (LHC) data on anisotropic flow. In particular, we show that, compared to standard Glauber-inspired calculations, our formalism provides a better description of the centrality dependence of the ratio of elliptic flow and triangular flow. It also naturally explains the evolution of elliptic flow fluctuations between RHIC and LHC energies.