Breaking Tri-Bimaximal Mixing and Large θ13

The long baseline neutrino experiment, T2K, and the reactor experiment, Double Chooz will soon present new data. If we expect sin theta(13) to be 0.1 - 0.2, which is close to the present experimental upper bound, we should not persist in the paradigm of the tri-bimaximal mixing. We discuss breaking the tri-bimaximal mixing by adding a simple mass matrix, which could be derived from some non-Abelian discrete symmetries. It is found that sin theta(13) = 0.1 - 0.2 is expected in our model independent analysis of the generalized mass matrix for the normal or inverted hierarchical neutrino mass spectrum. On the other hand, sin(2) theta(23) and sin(2) theta(12) are expected to be not far from 1/2 and 1/3, respectively. As a typical example, we also discuss the A(4) flavor model with the 1 and 1' flavons, which break the tri-bimaximal mixing considerably. In this modified version of the Altarelli and Feruglio model, sin theta(13) is predicted to be around 0.15 in the case of the normal hierarchical neutrino masses m(3) >> n2, m(1), and 0.2 in the case of the inverted hierarchy m(3) << m(2), m(1). The form of the neutrino mass matrix looks rather interesting it is suggestive of other discrete symmetries as well.