Neutrino-induced multilepton events arising from the associated production of charmed particles

We discuss the contribution of associated production of charmed pairs $\overline{c}c$ to multilepton events in $\nu$ reactions, with emphasis on like-sign dimuons and trimuons. Both absolute rates and constraints from distributions are considered. We give one treatment which is purely phenomenological, obtaining the maximum amount of $\overline{c}c$ production which can be consistent with existing data on distributions, and giving relative amounts for different multilepton states. We also attempt a theoretical analysis which gives an estimate for the magnitude of $\overline{c}c$ production in $\nu$ reactions starting from photoproduction of $\psi$; this leads to a rate significantly larger than that due to perturbative quantum-chromodynamics estimates made so far. We give results for both the 350-GeV wide-band neutrino beam at CERN and the 400-GeV quadrupole triplet neutrino beam at Fermilab, including experimental cuts. Our results for trimuons and dimuons arising from $\overline{c}c$ decays are that $\frac{\sigma \left({\mu }^{-}{\mu }^{-}{\mu }^{+}\right)}{\sigma \left({\mu }^{-}\right)}\lesssim 1\times {10}^{-5\mathrm{}}$ and $\frac{\sigma \left({\mu }^{-}{\mu }^{-}\right)}{\sigma \left({\mu }^{-}{\mu }^{+}\right)}\lesssim 2\times {10}^{-2\mathrm{}}$. We do not find any need to search for anomalous sources of multimuon events.