Predictions for flow harmonic distributions and flow factorization ratios at RHIC

TL;DR

This paper investigates flow harmonic distributions and factorization breaking ratios at RHIC, proposing these as orthogonal observables to better constrain initial conditions in relativistic hydrodynamics.

Contribution

It compares initial condition models NeXus and TRENTO, highlighting their differing predictions for factorization breaking ratios at RHIC, and emphasizes the importance of these observables.

Findings

Similar flow harmonic distributions at LHC and RHIC for both models

Significant differences in factorization breaking ratios at RHIC between models

Initial free streaming influences ratio predictions, especially at RHIC

Abstract

Data obtained at RHIC can be reproduced with relativistic viscous hydrodynamic simulations by adjusting the viscosity and initial conditions but it is difficult to disentangle these quantities. It is therefore important to find orthogonal observables to constrain the initial conditions separately from the viscosity. New observables have been measured at the LHC and shown to be sensitive to initial conditions and less to medium properties, specifically factorization breaking ratios appears to be promising. Here we consider two initial condition models, NeXus and TRENTO. While both models yield similar results for the scaled flow harmonic distributions both at the LHC and RHIC, they lead to quantitatively much more different patterns for the factorization breaking ratios at RHIC than at LHC, due to the shorter lifetime. Additionally, not only final state interactions but also initial free streaming matter in these ratio predictions and differences between these are enhanced at RHIC compared to LHC. Therefore experimental factorization breaking ratios at RHIC top energy (for transverse momentum) would be interesting to get.