Quark Mass Matrices in the A_4 Model
  If the standard model of quark interactions is supplemented by a discrete A_4 symmetry (which may be relevant for the lepton sector), the spontaneous breaking of the electroweak gauge symmetry allows arbitrary quark masses, but all mixing angles are predicted to be zero. A pattern of the explicit breaking of A_4 is proposed, which results in a realistic charged-current mixing matrix. 
Ernest Ma (UC Riverside)