Flavor Symmetry for Quarks and Leptons

Present data on neutrino masses and mixing favor the highly symmetric tribimaximal neutrino mixing matrix which suggests an underlying flavor symmetry. A systematic study of non-abelian finite groups of order $g\le 31$ reveals that tribimaximal mixing can be derived not only from the well known tetrahedral flavor symmetry $T\equiv A_4$, but also by using the binary tetrahedral symmetry $T^{{}^{\mathrm{\prime }}}\equiv S{L}_2(F_3)$ which does not contain the tetrahedral group as a subgroup. $T^{{}^{\mathrm{\prime }}}$ has the further advantage that it can also neatly accommodate the quark masses including a heavy top quark.