Event-shape fluctuations and flow correlations in ultra-relativistic heavy-ion collisions

TL;DR

This paper reviews recent experimental measurements of flow observables related to event-shape fluctuations and collective expansion in heavy-ion collisions, comparing them with theoretical models to enhance understanding of initial conditions and hydrodynamic responses.

Contribution

It provides a comprehensive classification of flow observables, summarizes experimental results, and discusses new fluctuation measurements to deepen insight into collision dynamics.

Findings

Qualitative agreement between hydrodynamic models and experimental data

Identification of linear and non-linear flow responses

Proposal of new fluctuation measurement techniques

Abstract

I review recent measurements of a large set of flow observables associated with event-shape fluctuations and collective expansion in heavy ion collisions. First, these flow observables are classified and experiment methods are introduced. The experimental results for each type of observables are then presented and compared to theoretical calculations. A coherent picture of initial condition and collective flow based on linear and non-linear hydrodynamic responses is derived, which qualitatively describe most experimental results. I discuss new types of fluctuation measurements that can further our understanding of the event-shape fluctuations and collective expansion dynamics.