Study of vector mesons in dimuon production in a large kinematic region in p W and S W interactions at 200-GeV/c/nucleon

Results are presented on ρ +ω , φ and J/Ψ production in p-W and 32S-W interactions at 200 GeV/c/nucleon measured via the dimuon decay in a large kinematic region. The data are normalized to the charged particle multiplicity in the same rapidity interval. They have been collected using the HELIOS/3 muon spectrometer at the CERN SPS. The ratio Bσ φ / (Bσ ρ + Bσ ω ), where B is the relevant resonance μ μ branching fraction, increases between proton and sulphur projectiles, and is somewhat enhanced going from peripheral to central S-W interactions. This results from an increase in the number of produced φ 's per charged particle. The ratio is measured in different intervals of p T and rapidity. It is not clearly dependent on p T, but is larger at higher rapidities. J/Ψ production, likewise normalized to charged multiplicity, is significantly lower in S-W compared to p-W interactions.