DOI: 10.1140/epjc/s2003-01135-3
Maximal atmospheric neutrino mixing in an SU(5) model
W. Grimus1 and L. Lavoura21 Universität Wien, Institut für Theoretische Physik, Boltzmanngasse 5, 1090 Wien, Austria
2 Universidade Técnica de Lisboa, Centro de Física das Interacções Fundamentais, Instituto Superior Técnico, 1049-001 Lisboa, Portugal
(Received: 29 November 2002 / Published online: 3 March 2003)
Abstract
We show that maximal atmospheric and large solar neutrino mixing
can be
implemented in
SU(5) gauge theories,
by making use of the
U(1)F symmetry
associated with a suitably defined family number
F,
together with a
symmetry which does not commute
with
F.
U(1)F is
softly broken by the mass terms of the right-handed neutrino
singlets, which are responsible for the seesaw mechanism;
in addition,
U(1)F is also spontaneously broken at the electroweak scale.
In our scenario, lepton mixing stems exclusively
from the right-handed-neutrino Majorana mass matrix,
whereas the CKM matrix originates solely in the up-type-quark
sector. We show that, despite the non-supersymmetric character
of our model,
unification of the gauge couplings can be achieved at a scale
;
indeed,
we have found
a particular solution to this problem which
yields results almost identical to the ones of
the minimal supersymmetric standard model.
© Società Italiana di Fisica, Springer-Verlag 2003
