Radiative and hadronic tetralepton production by neutrinos

We calculate characteristics of ..nu..N ..-->.. 4..mu..X and ..nu..N ..-->.. ..mu..3eX events in neutrino scattering, arising from conventional charm production accompanied by a dimuon pair from three sources: (i) radiation from the primary lepton-quark interaction, (ii) direct pair production from the subsequent hadronic interactions, deduced empirically from observed prompt muon-pair production in hadron-hadron collisions and (iii) charm-pair production from the primary lepton-quark interaction. Sources (i) and (ii) predict spectrum-averaged 4..mu.. rates of a few times 10/sup -8/ and ..mu..3e rates of order 10/sup -7/; (iii) is much smaller. These rates are smaller than the preliminary experimental estimates, but other characteristics of the two published tetralepton events are compatible with a radiative plus hadronic interpretation. We consider an additional hadronic contribution from F production with F ..-->.. phil..nu.. and phi ..-->.. ll-bar decays, that may contribute appreciably.