Neutral strange particle production in neutrino and antineutrino charged-current interactions on neon

Abstract

A study has been made of neutral strange particle production in ${\ensuremath{\nu}}_{\mathrm{\ensuremath{\mu}}}$Ne and \ensuremath{\nu}${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}_{\mathrm{\ensuremath{\mu}}}$Ne charged-current interactions at a higher energy than any previous study. The experiment was done at the Fermilab Tevatron using the 15-ft. bubble chamber, and the data sample consists of 814(154) observed neutral strange particles from 6263(1115) \ensuremath{\nu}(\ensuremath{\nu}\ifmmode\bar\else\textasciimacron\fi{}) charged-current events. For the \ensuremath{\nu} beam (average event energy 〈${\mathit{E}}_{\ensuremath{\nu}}$〉=150 GeV), the average multiplicities per charged-current event have been measured to be 0.408\ifmmode\pm\else\textpm\fi{}0.048 for ${\mathit{K}}^{0}$, 0.127\ifmmode\pm\else\textpm\fi{}0.014 for \ensuremath{\Lambda}, and 0.015\ifmmode\pm\else\textpm\fi{}0.005 for \ensuremath{\Lambda}\ifmmode\bar\else\textasciimacron\fi{}, which are significantly greater than for lower-energy experiments. The dependence of rates on kinematical variables has been measured, and shows that both ${\mathit{K}}^{0}$ and \ensuremath{\Lambda} production increase strongly with ${\mathit{E}}_{\ensuremath{\nu}}$, ${\mathit{W}}^{2}$, ${\mathit{Q}}^{2}$, and ${\mathit{y}}_{\mathit{B}}$. Compared to lower-energy experiments, single-particle distributions indicate that there is much more ${\mathit{K}}^{0}$ production for ${\mathit{x}}_{\mathit{F}}$>-0.2, and the enhanced \ensuremath{\Lambda} production spans most of the kinematic region. \ensuremath{\Lambda}\ifmmode\bar\else\textasciimacron\fi{} production is mostly in the region \ensuremath{\Vert}${\mathit{x}}_{\mathit{F}}$\ensuremath{\Vert}0.3. The Lund model is shown to be in qualitative agreement with the data, but does not reproduce single-particle distributions in detail. For ${\mathit{x}}_{\mathit{F}}$>-0.2 there is a significant excess of \ensuremath{\Lambda} production over the model's prediction. The \ensuremath{\Lambda} hyperons are found to be polarized in the production plane.