Event-by-event anisotropic flow in heavy-ion collisions from combined Yang-Mills and viscous fluid dynamics

TL;DR

This paper combines classical Yang-Mills theory with viscous hydrodynamics to accurately model anisotropic flow in heavy-ion collisions, matching experimental data from LHC and RHIC.

Contribution

It introduces a combined IP-Glasma and MUSIC model that captures event-by-event fluctuations and pre-equilibrium dynamics for the first time.

Findings

Model reproduces v_n data at LHC and RHIC

Accurately describes event-by-event v_2, v_3, v_4 distributions

Provides insights into glasma dynamics and QGP properties

Abstract

Anisotropic flow coefficients v_1-v_5 in heavy ion collisions are computed by combining a classical Yang-Mills description of the early time glasma flow with the subsequent relativistic viscous hydrodynamic evolution of matter through the quark-gluon plasma and hadron gas phases. The glasma dynamics, as realized in the IP-Glasma model, takes into account event-by-event geometric fluctuations in nucleon positions and intrinsic sub-nucleon scale color charge fluctuations; the pre-equilibrium flow of matter is then matched to the MUSIC algorithm describing viscous hydrodynamic flow and particle production at freeze-out. The IP-Glasma+MUSIC model describes well both transverse momentum dependent and integrated v_n data measured at the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC). The model also reproduces the event-by-event distributions of v_2, v_3 and v_4 measured by the ATLAS collaboration. The implications of our results for better understanding of the dynamics of the glasma as well as for the extraction of transport properties of the quark-gluon plasma are outlined.