Supersymmetric A4 x Z3 and A4 realizations of neutrino tribimaximal mixing without and with corrections

In an improved application of the tetrahedral symmetry A(4) first introduced by Ma and Rajasekaran, supplemented by the discrete symmetry Z(3) as well as supersymmetry, a two-parameter form of the neutrino mass matrix is derived which exhibits the tribimaximal mixing of Harrison, Perkins and Scott. This form is the same as the one obtained previously by Altarelli and Feruglio, and the inverse of that obtained by Babu and He. If only A(4) is used, then corrections appear, making tan(2) theta(12) different from 0.5, without changing significantly sin(2) 2 theta(23) from one or theta(13) from zero.