Tri-Bimaximal Neutrino Mixing and the $T_{13}$ Flavor Symmetry
  We present a supersymmetric $T_{13}$ model for the tri-bimaximal neutrino mixing, and the complete flavor group is $T_{13}\times Z_{4}\times Z_2$. At leading order, the residual symmetry of the charged lepton sector is $Z_3$, and the $T_{13}$ symmetry is broken completely in the neutrino sector. The charged lepton mass hierarchies are determined by the spontaneous breaking of the flavor symmetry, both the type I see-saw mechanism and the Weinberg operator contribute to generating the light neutrino masses. Tri-bimaximal mixing is exact at leading order while subleading contributions introduce corrections of order $\lambda^2_c$ to the three lepton mixing angles. The vacuum alignment and subleading corrections are studied in detail, a moderate hierarchy of order $\lambda_c$ between the vacuum expectation values of the flavon fields in the charged lepton and neutrino sectors can be accommodated. 
Gui-Jun Ding
hep-ph