Model-Independent Analysis of Tri-bimaximal Mixing -- a Softly-Broken Hidden or an Accidental Symmetry?

Abstract

To address the issue of whether tri-bimaximal mixing (TBM) is a softly-broken hidden or an accidental symmetry, we adopt a model-independent analysis in which we perturb a neutrino mass matrix leading to TBM in the most general way but leave the three texture zeros of the diagonal charged lepton mass matrix unperturbed. We compare predictions for the perturbed neutrino TBM parameters with those obtained from typical SO(10) grand unified theories with a variety of flavor symmetries. Whereas SO(10) GUTs almost always predict a normal mass hierarchy for the light neutrinos, TBM has a priori no preference for neutrino masses. We find, in particular for the latter, that the value of |U_{e3}| is very sensitive to the neutrino mass scale and ordering. Observation of |U_{e3}|^2 > 0.001 to 0.01 within the next few years would be incompatible with softly-broken TBM and a normal mass hierarchy and would suggest that the apparent TBM symmetry is an accidental symmetry instead. No such conclusions can be drawn for the inverted and quasi-degenerate hierarchy spectra.

14 pages, 8 figures. Typos corrected, references added. To appear in PLB

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Cited by in corpus (11)

• Possible Alternatives to Tri-bimaximal Mixing
• Comparing Trimaximal Mixing and Its Variants with Deviations from Tri-bimaximal Mixing
• Z_2 Symmetry Prediction for the Leptonic Dirac CP Phase
• Different SO(10) Paths to Fermion Masses and Mixings
• Deviations from Tri-bimaximal Mixing: Charged Lepton Corrections and Renormalization Group Running
• Neutrino masses and tribimaximal mixing in the minimal renormalizable supersymmetric SU(5) grand unified model with A4 flavor symmetry
• Large U_{e3} and Tri-bimaximal Mixing
• Theoretical Models of Neutrino Mixing: Recent Developments
• Deviations from tri-bimaximal mixing
• Neutrino Mass Models: a road map
• Perspectives in Neutrino Physics