New-Particle Decays andμeKEvents

We consider the possible role of $Y\to \mathrm{Ke}\nu$ new-particle decays in the ${\mu }^{-}{e}^{+}{K}_s$ events in neutrino bubble-chamber experiments. We calculate transverse momentum distributions of $e$ and $K$, including effects of initial $Y$-particle transverse motion, and invariant $K-e$ mass distributions. We also calculate the $E_e$ spectrum in a current-fragmentation model, and estimate expected $\mu e$ event rates from dimuon event rates assuming that they have a common origin.