Global Observations from PHOBOS

Abstract

Particle production in Au+Au collisions has been measured in the PHOBOS experiment at RHIC for a range of collision energies. Three empirical observations have emerged from this dataset which require theoretical examination. First, there is clear evidence of limiting fragmentation. Namely, particle production in central Au+Au collisions, when expressed as $dN/d{\eta }^{\prime }$ (${\eta }^{\prime }\equiv \eta -y_{beam}$), becomes energy independent at high energy for a broad region of ${\eta }^{\prime }$ around ${\eta }^{\prime }=0$. This energy-independent region grows with energy, allowing only a limited region (if any) of longitudinal boost-invariance. Second, there is a striking similarity between particle production in e+e- and Au+Au collisions (scaled by the number of participating nucleon pairs). Both the total number of produced particles and the longitudinal distribution of produced particles are approximately the same in e+e- and in scaled Au+Au. This observation was not predicted and has not been explained. Finally, particle production has been found to scale approximately with the number of participating nucleon pairs for $N_{part}>65$. This scaling occurs both for the total multiplicity and for high $\pT$ particles (3 $<\pT<$ 4.5 GeV/c).

QM2002 plenary talk, 10 pages, 11 figures

References in corpus (1)

• Silicon Pad Detectors for the PHOBOS Experiment at RHIC

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