Obtaining nonvanishing $\theta_{13}$ with constrained neutrino Yukawa matrix and implications for flavor model buildings
Assuming a diagonal Majorana neutrino mass matrix, we investigate the neutrino Yukawa textures which lead to a non-zero reactor mixing angle $\theta_{13}$. The neutrino effective coupling matrix $\kappa^{eff}$ is pre-diagonalized by a constant mixing pattern $V_{\nu}$ with a vanishing $\theta^{\nu}_{13}$. The resulting pre-diagonal symmetrical matrix $\kappa$ is set to be four texture zeros with two types of off-diagonal elements nonzero, which is $\kappa_{13}$ and $\kappa_{23}$, respectively. With the expectation of simple textures we thoroughly classify the linear combinations, $\alpha_{i}$, $\beta_{i}$ and $\gamma_{i}$ of Yukawa elements $\lambda_{ij}$ in a same row, according to the values vanishing or not. Each set of the classifications can lead to a Yukawa texture which may have implications for the discrete flavor model buildings. We also present a model based on $A_{4}$ according to one set of the constraints on the three combinations with a specific choice of a coefficient in Yukawa texture.