Flow harmonics in heavy ion physics at CMS and ATLAS

TL;DR

This paper reviews measurements of flow harmonics in heavy ion, proton-nucleus, and proton-proton collisions at CMS and ATLAS, exploring the hydrodynamic response, initial geometry, and particle flow correlations.

Contribution

It provides an experimental overview of anisotropic flow measurements across different collision systems, highlighting insights into the medium's properties and initial state effects.

Findings

Flow measurements indicate a hydrodynamic response in heavy ion collisions.

Evidence of collective behavior in small systems like proton-proton collisions.

Discrimination between initial momentum correlations and flow effects is discussed.

Abstract

How can we gain a detailed insight into the hydrodynamic response of the system created in heavy ion collisions to the fluctuating initial geometry and viscous effects? Do we create a strongly interacting medium in proton-nucleus and proton-proton collisions, or rather a system of partons undergoing few scatterings? To what extent can we discriminate between initial momentum correlations and flow generated as a response to the initial geometry via interactions in the final state? Do measurements of identified particle flow confirm the observations from inclusive charged hadrons? An experimental overview of anisotropic flow measurements, ranging from large down to the smallest collision systems, is given in these proceedings.