Scaling of elliptic flow in heavy ion collisions

TL;DR

This paper examines the scaling behavior of elliptic flow ($v_2$) in heavy ion collisions, questioning the traditional hydrodynamic and energy loss models by analyzing their consistency with experimental scaling across energy, rapidity, and system size.

Contribution

It challenges existing interpretations of $v_2$ by exploring how observed scaling patterns may not align with current models, suggesting a need for revised understanding.

Findings

$v_2$ exhibits simple scaling with energy, rapidity, and system size in experiments.

Traditional models struggle to fully explain the observed scaling behavior.

Reconciliation of models with experimental data remains complex.

Abstract

The common interpretation of $v_2$ in heavy ion collisions is that it is produced by hydrodynamic flow at low transverse momentum and by parton energy loss at high transverse momentum. In this talk we discuss this interpretation in view of the dependence of $v_2$ with energy, rapidity and system size, and show that it might not be trivial to reconcile these models with the relatively simple scaling found in experiment