Quest for new physics in flavor mixing and Dirac neutrino masses

We show that a unified description of the observed patterns of quark and lepton mixing can be achieved if the flavor group $D_n$ and CP symmetry are broken to $Z_2\times CP$ in the neutrino, charged lepton, up quark as well as down quark sectors, and the smallest group is $D_{14}$. We also perform a systematic study of how a dimension six operator $\overline{L}\widetilde{H}\nu_{R}\left(H^{\dagger}H\right)$ for Dirac neutrino masses may occur at tree level and in one loop.