Collective Flow of QCD Matter: a Historical Introduction

TL;DR

This paper reviews the historical development of understanding collective flow in QCD matter through experimental and theoretical advances from early nuclear collision studies to recent RHIC and LHC research.

Contribution

It provides a comprehensive historical overview of the evolution of observables and theories related to collective hydrodynamic flow in relativistic nuclear collisions.

Findings

Progression from early radial and directed flow discoveries to modern high-energy collision studies.

Development of experimental techniques to measure collective flow.

Advances in theoretical models explaining hydrodynamic behavior in QCD matter.

Abstract

We present a historical review of the physics observables developed for relativistic nuclear collisions, that describe collective hydrodynamic flow of hadronic or partonic matter, and of the corresponding experimental progress. We begin with the early discovery phase of radial and directed flow at the Bevalac, and continue the review until the recent work at RHIC and LHC, and related theory.