Tetrahedral Family Symmetry and the Neutrino Mixing Matrix

In a new application of the discrete non-Abelian symmetry A 4 using the canonical seesaw mechanism, a three-parameter form of the neutrino mass matrix is derived. It predicts the following mixing angles for neutrino oscillations: θ 13 =0, sin 2 θ 23 =1/2, and sin 2 θ 12 close, but not exactly equal to 1/3, in one natural symmetry limit.