Generalized tri-bimaximal neutrino mixing and its sensitivity to radiative corrections

Abstract We argue that the tri-bimaximal neutrino mixing pattern V 0 or its generalized form V 0 ′ , which includes two arbitrary Majorana phases of CP violation, may result from an underlying flavor symmetry at a superhigh energy scale close to the seesaw scale ( ∼ 10 14 GeV ) . Taking the working assumption that three neutrino masses are nearly degenerate, we calculate radiative corrections to V 0 and V 0 ′ in their evolution down to the electroweak scale ( ∼ 10 2 GeV ) . Three mixing angles of V 0 or V 0 ′ are essentially stable against radiative corrections in the standard model (SM). In the minimal supersymmetric standard model (MSSM), however, V 0 is in general disfavored and V 0 ′ can be compatible with current neutrino oscillation data if its two Majorana phases α 1 and α 2 are properly fine-tuned. We also find that it is possible to radiatively generate the CP-violating phase δ from α 1 and α 2 , and δ may keep on staying at its quasi-fixed point in either the SM or the MSSM.