Anisotropic flow in ultra-relativistic heavy ion collisions
  A sign reversal of the directed flow parameter $v_1$ in the central rapidity region in Au+Au collisions at $\sqrt s =200$~AGeV is predicted. This anti-flow is shown to be linked to the expansion of the hot matter created. In line with this observation the predicted elliptic flow parameter $v_2$ of various particle species is predicted and linked to the mean free path of these particles. 
M. Bleicher, H. St\"ocker (LBNL, Frankfurt Univ.)