Probing bulk properties and partonic collectivity via multi-strange baryons in Au+Au collisions at top RHIC energy

The study of the multi-strange baryon production in the final state of ultra-relativistic Au+Au collisions at sNN=200GeV at RHIC gives information on the freeze-out conditions and probably on earlier stages of the collision. Chemical freeze-out temperature Tch as well as the strangeness phase space occupancy factor γs extracted from statistical models are studied as a function of the collision centrality. γs saturates at 1 in most central collisions suggesting an equilibration of strange quarks in the medium. A study of the collective motion of the collision is possible in the framework of a hydrodynamically-inspired model which considers the particles to be emitted from a locally thermalized system. In this view, multi-strange particles seem to develop significant radial transverse flow but smaller than π,K,p. Furthermore, Ξ−+Ξ¯+ and Ω−+Ω¯+ present an elliptic flow as strong as for previously measured baryons supporting the idea that a fraction of the final collective motion has been developed at an early partonic stage of the collision.