Elliptic Flow: A Study of Space-Momentum Correlations In Relativistic Nuclear Collisions

TL;DR

This paper reviews measurements of elliptic flow (v2) in heavy-ion collisions, highlighting its role as an indicator of space-momentum correlations and Quark Gluon Plasma expansion across various energies.

Contribution

It provides a comprehensive review of v2 measurements, their scaling behaviors, and comparisons with hydrodynamic models in relativistic nuclear collisions.

Findings

v2 indicates strong space-momentum correlations

Data supports rapid expansion of Quark Gluon Plasma

Hydrodynamic models describe observed flow patterns

Abstract

Here I review measurements of v2, the second component in a Fourier decomposition of the azimuthal dependence of particle production relative to the reaction plane in heavy-ion collisions. v2 is an observable central to the interpretation of the subsequent expansion of heavy-ion collisions. Its large value indicates significant space-momentum correlations, consistent with the rapid expansion of a strongly interacting Quark Gluon Plasma. Data is reviewed for collision energies from sqrt[sNN] = 2 to 200 GeV. Scaling observations and comparisons to hydrodynamic models are discussed.