Nu micro- nu e universality in charged-current neutrino interactions.

Abstract

A total of $1403{\ensuremath{\nu}}_{e}$ and $179{\overline{\ensuremath{\nu}}}_{e}$ charged-current interactions with energies ranging up to 200 GeV were observed in a wideband neutrino-beam experiment using the Fermilab 15-ft bubble chamber filled with a heavy Ne-${\mathrm{H}}_{2}$ mix. As a test of ${\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{-}{\ensuremath{\nu}}_{e}$ universality, these events were compared to samples of ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ and ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ charged-current events obtained during the same experiment. The ${\ensuremath{\nu}}_{e}\ensuremath{-}\mathrm{to}\ensuremath{-}{\ensuremath{\nu}}_{\ensuremath{\mu}}$ cross-section ratio was measured to be 1.09\ifmmode\pm\else\textpm\fi{}0.17, and the corresponding ratio for antineutrinos was 1.46\ifmmode\pm\else\textpm\fi{}0.34. Kinematic distributions and charged-particle multiplicities were also consistent with universality. The neutral-strange-particle production rate was measured to be (11.7\ifmmode\pm\else\textpm\fi{}1.2)% for ${\ensuremath{\nu}}_{e}$ and (5.2\ifmmode\pm\else\textpm\fi{}2.2)% for ${\overline{\ensuremath{\nu}}}_{e}$, in good agreement with the ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ and ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ rates. The relative rate for ${e}^{\ensuremath{-}}{e}^{+}$ dilepton production by ${\ensuremath{\nu}}_{e}$ was (0.82\ifmmode\pm\else\textpm\fi{}0.47)%, also consistent with universality. The rate for neutral-strange-particle production in ${e}^{\ensuremath{-}}{e}^{+}$ dilepton events is reported for the first time. The measured rate of 0.64\ifmmode\pm\else\textpm\fi{}0.45 agrees with the value expected from universality.