Intrinsic deviation from the tri-bimaximal neutrino mixing in a class of A4 flavor models

It is well known that the tri-bimaximal neutrino mixing pattern V0 can be derived from a class of flavor models with the non-Abelian A4 symmetry. We point out that small corrections to V0, which are inherent in the A4 models and arise from both the charged-lepton and neutrino sectors, have been omitted in the previous works. We show that such corrections may lead the 3×3 neutrino mixing matrix V to a non-unitary deviation from V0, but they cannot result in a nonzero value of θ13 or any new CP-violating phases. Current experimental constraints on the unitarity of V allow us to constrain the model parameters to some extent.