Neutrino masses from an A4 symmetry in holographic composite Higgs models

We show that holographic composite Higgs Models with a discrete A(4) symmetry can be built, which naturally predict hierarchical charged lepton masses and an approximate tri-bimaximal lepton mixing with the correct scale of neutrino masses and a characteristic phenomenology. They also satisfy current constraints from electroweak precision tests, lepton flavor violation and lepton mixing in a large region of parameter space. Two features arise in our model phenomenologically relevant. First, an extra suppression on the lepton Yukawa couplings makes the tau lepton more composite than naively expected from its mass. As a consequence new light leptonic resonances, with masses as low as few hundreds of GeV, large couplings to tau and a very characteristic collider phenomenology, are quite likely. Second, the discrete symmetry A(4) together with the model structure provide a double-layer of flavor protection that allows to keep tree-level mediated processes below present experimental limits. One-loop processes violating lepton flavor, like mu -> e gamma, may be however observable at future experiments.