Micro-e+ dilepton production in charged-current nu micro interactions.

Abstract

The production of ${\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+}$ dileptons by muon neutrinos is studied in a high-statistics bubble-chamber experiment. The experiment consisted of exposing the Fermilab 15-ft bubble chamber filled with a heavy Ne-${\mathrm{H}}_{2}$ mix to a wideband neutrino beam. In a total sample of 146 700\ifmmode\pm\else\textpm\fi{}11 700 charged-current interactions, 461 events with an ${e}^{+}({P}_{{e}^{+}}>300 \mathrm{MeV}/c)$ and a ${\ensuremath{\mu}}^{\ensuremath{-}}$ are observed. The rate for ${\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+}$ dilepton production in measured to be (0.42\ifmmode\pm\else\textpm\fi{}0.06)%. The energy dependence of this rate is presented. The kinematic distributions for the ${\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+}$ events are consistent with charm production and subsequent semileptonic decay. A total of 60 ${K}_{S}^{0}$ and 31 ${\ensuremath{\Lambda}}^{0}$ decays were observed in the ${\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+}$ event sample. The measured rates for neutral-strange-particle production are 0.78\ifmmode\pm\else\textpm\fi{}0.12 $\frac{{K}^{0}}{{\overline{K}}^{0}}'\mathrm{s}$ and 0.19\ifmmode\pm\else\textpm\fi{}0.04 ${\ensuremath{\Lambda}}^{0}'\mathrm{s}$ per ${\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+}$ event. Finally, rates for ${\ensuremath{\Lambda}}_{c}^{+}$, ${D}^{0}$, and ${D}^{+}$ production in charged-current ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ interactions are derived. They are found to be (${4}_{\ensuremath{-}2}^{+10}$)%, (${1.7}_{\ensuremath{-}0.7}^{+0.5}$)%, and (${1.3}_{\ensuremath{-}0.5}^{+0.4}$)%, respectively.