Exposing the Noncollectivity in Elliptic Flow

Jinfeng Liao, Volker Koch

Published 2009-02-13, updated 2009-07-24Version 2

We show that backward-forward elliptic anisotropy correlation provides an experimentally accessible observable which distinguishes between collective and non-collective contributions to the observed elliptic anisotropy $v_2$ in relativistic heavy ion collisions. The measurement of this observable will reveal the momentum scale at which collective expansion seizes and where the elliptic anisotropy is dominated by (semi)-hard processes.