2 research outputs found
A Model of Lepton Masses from a Warped Extra Dimension
In order to explain the non-hierarchical neutrino mixing angles and the
absence of lepton flavor violating processes in the context of warped extra
dimensions one needs to introduce bulk flavor symmetries. We present a simple
model of lepton masses and mixings in RS models based on the A4 non-abelian
discrete symmetry. The virtues of this choice are: (i) the natural appearance
of the tri-bimaximal mixing pattern; (ii) the complete absence of tree-level
flavor violations in the neutral sector; (iii) the absence of flavor gauge
bosons; (iv) the hierarchies in the charged lepton masses are explained via
wave-function overlaps. We present the minimal field content and symmetry
breaking pattern necessary to obtain a successful model of this type. The
bounds from electroweak precision measurements allow the KK mass scale to be as
low as 3 TeV. Tree-level lepton flavor violation is absent in this model, while
the loop induced mu -> e gamma branching fraction is safely below the
experimental bound
A Simplest A4 Model for Tri-Bimaximal Neutrino Mixing
We present a see-saw model for Tri-Bimaximal mixing which is based on a
very economical flavour symmetry and field content and still possesses all the
good features of models. In particular the charged lepton mass
hierarchies are determined by the flavour symmetry itself
without invoking a Froggatt-Nielsen U(1) symmetry. Tri-Bimaximal mixing is
exact in leading order while all the mixing angles receive corrections of the
same order in next-to-the-leading approximation. As a consequence the predicted
value of is within the sensitivity of the experiments which will
take data in the near future. The light neutrino spectrum, typical of
see-saw models, with its phenomenological implications, also including
leptoproduction, is studied in detail.Comment: 20 pages, 2 figure