Origin of trimuon events in high-energy neutrino interactions

Abstract The properties of 76 neutrino-initiated μ − μ − μ + events observed in the CDHS detector in the 350 GeV and 400 GeV wide-band beams at the CERN SPS are discussed. For neutrino energies > 30 GeV and muon momenta ≳ 4.5 GeV, the average trimuon rate is (3.0±0.4)×10 −5 of the single-muon event rate. The data are in agreement with normal charged-current interactions with the additional production of a muon pair by both hadronic and radiative processes. No evidence is found for either heavy-lepton or heavy-quark cascades. Upper limits for these two possibilities are established.