CAFPE-128/10 UGFT-258/10 arXiv:1001.5151v2 [hep-ph] 10 Feb 2010 Neutrino Masses from an A$_{4}$ Symmetry in Holographic Composite Higgs Models Francisco del ´ Aguila, 1 Adri´ an Carmona, 1 and Jos´e Santiago 1, 2 1 CAFPE and Departamento de F´ısica Te´ orica y del Cosmos, Universidad de Granada, E-18071 Granada, Spain $^{2}$Institute for Theoretical Physics, ETH, CH-8093, Z¨ urich, Switzerland (Dated: October 10, 2018) We show that holographic composite Higgs Models with a discrete A$_{4}$ symmetry naturally pre- dict hierarchical charged lepton masses and an approximate tri-bimaximal lepton mixing with the correct scale of neutrino masses. They also satisfy current constraints from electroweak precision tests, lepton flavor violation and lepton mixing in a large region of parameter space. Two phe- nomenologically relevant features arise in these models. First, an extra suppression on the lepton Yukawa couplings makes the τ 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 cou- plings to τ 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 µ → eγ , may be however observable at future experiments. Abstract 1