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

Abstract

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 +0.25and 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<0.8 ×10 −12s at 90% C.L.