Collective flow in single-hit QCD kinetic theory

TL;DR

This paper investigates collective flow phenomena in small collision systems using weakly coupled QCD kinetic theory, deriving a scaling formula and analyzing the centrality dependence of elliptic flow across different collision types.

Contribution

It introduces a parametric scaling formula for harmonic flow in small systems within QCD kinetic theory, extending understanding beyond previous toy models.

Findings

Derived a scaling relation for harmonic flow across system sizes.

Calculated the centrality dependence of elliptic flow in various collision systems.

Compared full QCD kinetic theory with simplified toy models.

Abstract

Motivated by recent interest in collectivity in small systems, we calculate the harmonic flow response to initial geometry deformations within weakly coupled QCD kinetic theory using the first correction to the free-streaming background. We derive a parametric scaling formula that relates harmonic flow in systems of different sizes and different generic initial gluon distributions. We comment on similarities and differences between the full QCD effective kinetic theory and the toy models used previously. Finally we calculate the centrality dependence of the integrated elliptic flow $v_2$ in oxygen-oxygen, proton-lead and proton-proton collision systems.