DOI 10.1007/s100520000292
The decays
and
of massive neutrinos
Q. Ho-Kim1 - B. Machet2,3, - X.Y. Pham2,3
1 Department of Physics, Université Laval (Québec),
Sciences and Engineering Building, Sainte Foy,
QC G1K7P4, Canada
2 Laboratoire de Physique Théorique et Hautes Energies,
LPTHE tour 16/1
étage,
Université P. et M. Curie, BP 126,
4 place Jussieu,
75252 Paris Cedex 05, France
3 Universités Pierre et Marie Curie (Paris 6) et Denis
Diderot (Paris 7), Unité associée au CNRS UMR 7589, Paris,
France
Received: 19 August 1999 / Published online: 3 February 2000 - © Springer-Verlag 2000
Abstract
If, as recently reported by the Super-Kamiokande
collaboration, the neutrinos are massive, the heaviest one, ,
would not
be stable and, though chargeless, could in particular decay
into a lighter neutrino
and a photon by quantum loop
effects.
The corresponding rate is computed in the standard model with
massive Dirac
neutrinos as a function of the neutrino masses and mixing angles.
The lifetime of the decaying neutrino is estimated
to be
years for a mass
eV.
Before the mass range arising from present experiments on neutrino
oscillations is definitively settled, it is still motivating
to study the
decay; if kinematically possible,
it
occurs at tree level and its one-loop radiative corrections
get enhanced by a large logarithm of the electron mass acting
as
an infrared cutoff. Thus the
decay
largely dominates the
one
by several orders of magnitude, corresponding to a lifetime
year for a mass of
MeV.
Copyright Società Italiana di Fisica, Springer-Verlag 2000