Study of neutrino-induced dimuon events in gargamelle at CERN-SPS

This letter reports a study of 117 opposite-sign and 41 like-sign dimuons, in a wide-band neutrino exposure of Gargamelle at CERN SPS. No signal is found in the μ − μ − channel. The μ − μ + channel is found to be dominated by D-meson production and decay. There is evidence in these events for missing energy which may be interpreted as an unseen neutrino. The V 0 multiplicities, K 0 /event=0.53 −0.20 +0.25 and Λ /event=0.03 −0.04 +0.06 show only evidence for charmed meson production. Information on the D-meson fragmentation function is presented. In a specific model, a rate σ (μ − μ + ) σ(μ − ) =(0.72±0.14×10 −2 is found, independent of the energy. An investigation of these events for visible D-decays sets a limit on the life-time τ D −12 s at 90% C.L.