Tri-bimaximal neutrino mixing and quark masses from a discrete flavour symmetry Original Research Article

We build a supersymmetric model of quark and lepton masses based on the discrete flavour symmetry group image, the double covering of image. In the lepton sector our model is practically indistinguishable from recent models based on image and, in particular, it predicts a nearly tri-bimaximal mixing, in good agreement with present data. In the quark sector a realistic pattern of masses and mixing angles is obtained by exploiting the doublet representations of image, not available in image. To this purpose, the flavour symmetry image should be broken spontaneously along appropriate directions in flavour space. In this paper we fully discuss the related vacuum alignment problem, both at the leading order and by accounting for small effects coming from higher-order corrections. As a result we get the relations: image and image.