The little bang! results from RHIC

Abstract

I report first results on Au + Au collisions at = 130 GeV/ per nucleon pair from all four experiments at the Relativistic Heavy Ion Collider. The energy density achieved is well above the threshold predicted by Lattice QCD for quark deconfinement. Large pressure is developed early in the collision, leading to collective asymmetric ow of the particle transverse to the beam energy and explosive expansion of the hot system. The hadron yields indicate presence of an equilibrated hadron gas in which the chemistry is fixed at a temperature near 170 MeV, which is also the temperature at which the quark gluon plasma to hadron phase transition is expected. A deficit of high transverse momentum particles is observed in central Au+Au collisions, compared to expected yields from independent nucleon-nucleon collisions or expectations from peripheral Au+Au collisions. This is likely the first indication of jet quenching by energy loss of hard scattered partons traversing the dense medium created in the collision