Fermion mass hierarchies and flavour mixing from a minimal discrete symmetry Original Research Article

We construct a simple model of fermion masses based on a spontaneously broken image flavour group. At the leading order, in the neutrino sector image is broken down to a image parity subgroup that enforces a maximal atmospheric mixing angle and a vanishing image. In the charged lepton sector the image parity is maximally broken and the resulting mass matrix is nearly diagonal. The charged lepton mass hierarchy is automatically reproduced by the image symmetry breaking parameter alone. A careful analysis shows that, after the inclusion of all relevant subleading effects, the model predicts image and image, image denoting the Cabibbo angle. A simple extension to the quark sector is also illustrated, where the mass spectrum and the mixing angles are naturally reproduced, with the exception of the mixing angle between the first two generations, that requires a small accidental enhancement.