Softly brokenA4symmetry for nearly degenerate neutrino masses

Abstract
The leptonic Higgs doublet model of neutrino masses is implemented with an A4 discrete symmetry (the even permutation of four objects or equivalently the symmetry of the tetrahedron) which has four irreducible representations: 1¯,1¯,1¯, and 3¯. The resulting spontaneous and soft breaking of A4 provides a realistic model of charged-lepton masses as well as a nearly degenerate neutrino mass matrix. The phenomenological consequences at and below the TeV scale are discussed.
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