Constraining models of initial conditions with elliptic and triangular flow data

Abstract

We carry out a combined analysis of elliptic and triangular flow data using viscous relativistic hydrodynamics. We show that these data allow us to put tight constraints on models of the early dynamics of a nucleus-nucleus collision. Specifically, the rms values of the initial ellipticity ${\ensuremath{\varepsilon}}_{2}$ and the initial triangularity ${\ensuremath{\varepsilon}}_{3}$ are constrained to lie within a narrow band for each centrality. We use these constraints as a filter for existing Monte Carlo models of initial state, and provide a simple test that can be performed on any candidate model to determine its compatibility with data.