v4 from ideal and viscous hydrodynamic simulations of nuclear collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC)

TL;DR

This study uses hydrodynamic simulations to analyze the ratio v4/(v2)^2 in nuclear collisions, examining its sensitivity to model parameters and comparing with experimental data from RHIC and LHC.

Contribution

It provides new insights into the sensitivity of v4/(v2)^2 to viscosity and initial conditions, and offers predictions for LHC collisions.

Findings

v2 is sensitive to initial eccentricity and viscosity

v4/(v2)^2 is insensitive to initial eccentricity

Viscous effects do not always increase v4/(v2)^2

Abstract

We compute v4/(v2)^2 in ideal and viscous hydrodynamics. We investigate its sensitivity to details of the hydrodynamic model and compare the results to experimental data from RHIC. Whereas v2 has a significant sensitivity only to initial eccentricity and viscosity while being insensitive to freeze out temperature, we find that v4/(v2)^2 is quite insensitive to initial eccentricity. On the other hand, it can still be sensitive to shear viscosity in addition to freeze out temperature, although viscous effects do not universally increase v4/(v2)^2 as originally predicted. Consistent with data, we find no dependence on particle species. We also make a prediction for v4/(v2)^2 in heavy ion collisions at the LHC.