A model of lepton masses from a warped extra dimension

Abstract

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 A 4 non-abelian discrete symmetry. The virtues of this choice are: the natural appearance of the tri-bimaximal mixing pattern; the complete absence of tree-level flavor violations in the neutral sector; the absence of flavor gauge bosons; 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 μ → eγ branching fraction is safely below the experimental bound. © 2008 SISSA.