Kl3+ decays involving finite neutrino mass and mass mixing.

Abstract

${K}_{l3}^{+}$ decays with the inclusion of effects of finite neutrino mass and mass mixing have been investigated. Predictions have been obtained for (i) pion energy spectrum, (ii) decay probability, (iii) \ensuremath{\pi}-l (=e,\ensuremath{\mu}) angular correlations, (iv) \ensuremath{\pi}-l energy correlations, (v) lepton energy spectrum, (vi) \ensuremath{\pi}-${\ensuremath{\nu}}_{i}$ (i=e,\ensuremath{\mu},\ensuremath{\tau}) angular correlations, and (vii) \ensuremath{\pi}-${\ensuremath{\nu}}_{i}$ energy correlations. Finite-mass effects are substantial in all the parameters discussed, whereas the mixing effects are discernible only in \ensuremath{\pi}-${\ensuremath{\nu}}_{i}$ angular and energy correlations. The mass limits for the ${\ensuremath{\nu}}_{3}$ mass for hierarchical mixing are found to be 174.0\ifmmode\pm\else\textpm\fi{}0.9 MeV and 120\ifmmode\pm\else\textpm\fi{}2 MeV for electronic and muonic modes, respectively, with nearly identical values for Kobayashi-Maskawa mixing.