W. Grimus, L. Lavoura
Abstract
We construct a model for tri-bimaximal lepton mixing which employs only family symmetries and their soft breaking; neither vacuum alignment nor supersymmetry, extra dimensions, or non-renormalizable terms are used in our model. It is an extension of the Standard Model making use of the seesaw mechanism with five right-handed neutrino singlets. The scalar sector comprises four Higgs doublets and one complex gauge singlet. The horizontal symmetry of our model is based on the permutation group S₃ of the lepton families together with the three family lepton numbers--united this constitutes a symmetry group Delta(6∞²). The model makes no predictions for the neutrino masses.