CP violation in neutrino mixing with δ = -π/2 in A4 Type-II seesaw model

We study a class of models for neutrino mass matrix in Type-II seesaw with A(4) family symmetry. The resulting neutrino mass matrix can be naturally made to respect a mu-tau exchange plus CP conjugate symmetry (GLS) with the CP violating phase delta and the mixing angle theta(23) predicted to be +/-pi/2 and pi/4, respectively. When GLS is explicitly broken by complex Yukawa couplings, the model predictions for delta and theta(23) can be significantly modified. Should future experiments indeed determine theta(23) and delta(CP) away from the GLS limit values, one then had to consider models with broken GLS. We study several simple scenarios to show how the modifications arise when GLS is broken and how future experiments can test this class of models. (C) 2015 The Authors. Published by Elsevier B.V.