Neutrino oscillations with three-generation mixings and mass hierarchy

Abstract

We have analyzed the results of reactor and accelerator neutrino oscillation experiments in a model with mixing of three neutrino fields and a neutrino mass hierarchy. It is shown that ${\nu }_{\mu }\leftrightarrows {\nu }_e$ oscillations with $0.6\le \Delta m^2\le 100{\mathrm{eV}}^2$ and amplitude larger than $2\times 10^{-3}$ are not compatible with the existing limits on neutrino oscillations if the non-diagonal elements of the mixing matrix are small. Thus, if the excess of positron events recently observed in the LSND experiment is due to ${\bar{\nu }}_{\mu }\to {\bar{\nu }}_e$ oscillations, the mixing in the lepton sector is basically different from the CKM mixing of quarks.

Comments: Latex file, 6 pages including 1 figure. The postscript file of text and figures is available at http://www.to.infn.it/teorici/giunti/papers.html or ftp://ftp.to.infn.it/pub/giunti/1995/dftt-83-95/dftt-83-95.ps