Flow in ultra-relativistic heavy ion collisions

Abstract

Flow develops in ultra-relativistic heavy-ion collisions via re-interactions among partons or/and hadrons. Characterizing flow is a crucial step towards understanding the formation of partonic matter. We review new measurements on anisotropic flow, including v2 at large rapidity, v1, v4, and new ways of addressing non-flow issues. We then show the self-consistency of the data and characterize flow of pions, kaons, protons and Xi within the Blast Wave parameterization. Finally, we show that the data currently available suggests that flow develops at both partonic and hadronic stages.