Large Lepton Mixings from Continuous Symmetries

Abstract

Within the broad context of quark-lepton unification, we investigate the implications of broken continuous family symmetries which result from requiring that in the limit of exact symmetry, the Dirac mass matrices yield hierarchical masses for the quarks and charged leptons, but lead to degenerate light neutrino masses as a consequence of the seesaw mechanism, without requiring hierarchical right-handed neutrino mass terms. Quark mixing is then naturally small and proportional to the size of the perturbation, but lepton mixing is large as a result of degenerate perturbation theory, shifted from maximal mixing by the size of the perturbation. Within this approach, we study an illustrative two-family prototype model with an SO(2) family symmetry, and discuss extensions to three-family models.

23 pages

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Cited by in corpus (8)

• Icosahedral (A5) Family Symmetry and the Golden Ratio Prediction for Solar Neutrino Mixing
• Hints on the high-energy seesaw mechanism from the low-energy neutrino spectrum
• Stitching an Asymmetric Texture with ${\mathcal{T}}_{13}\times {\mathcal{Z}}_5$ Family Symmetry
• Spontaneous R-Parity Violation, $A_4$ Flavor Symmetry and Tribimaximal Mixing
• Leptogenesis from the Asymmetric Texture
• Tribimaximal Mixing in the $SU(5)\times {\mathcal{T}}_{13}$ Texture
• Low-scale Resonant Leptogenesis in $SU(5)$ GUT with ${\mathcal{T}}_{13}$ Family Symmetry
• Spontaneous R-parity violating type III seesaw