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

Angelis, A. L. S.; Antos, J.; Beaulieu, M.; Beker, H.; Briskin, G.; Bystricky, J.; Catanesi, M. G.; Cerello, P.; Dagan, S.; Dellacasa, G.; Diehl, M.; Di Liberto, S.; Dolgoshein, B.; Esten, M.; Fabjan, C. W.; Gaidot, A.; Gallio, Mauro; Giubellino, P.; Goerlach, U.; Guerra, C.; Hamel, L. A.; Konovalov, S.; Kralik, I.; London, G.; Martelli, F.; Martin, J. P.; Masera, Massimo; Mazzoni, M. A.; Meddi, F.; Muciaccia, M. T.; Muraviev, S.; Nomerotsky, A.; Oren, Y.; Pansart, J. P.; Poulard, G.; Ramello, L.; Riccati, L.; Rosa, G.; Sandor, L.; Sarris, M.; Scomparin, E.; Shmeleva, A.; Simone, S.; Smirnov, S.; Taras, P.; Urban, J.; Vercellin, Ermanno

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.