2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/188276Stimulated by Ma's idea which explains the tribimaximal neutrino mixing by assuming an A_4 flavor symmetry, a lepton mass matrix model is investigated. A Frogatt-Nielsen type model is assumed, and the flavor structures of the masses and mixing are caused by the VEVs of SU(2)_L-singlet scalars ϕ_i^u and ϕ_i^d (i=1,2,3), which are assigned to {\bf 3} and ({\bf 1}, {\bf 1}',{\bf 1}'') of A_4, respectively.13 pages including 1 table, errors in Sec.7 correctedHigh Energy Physics - Phenomenologytext