Large ${\theta }_{13}^{\nu }$ and Unified Description of Quark and Lepton Mixing Matrices

We present a revised version of the so-called “yukawaon model”, which was proposed for the purpose of a unified description of the lepton mixing matrix $U_{PMNS}$ and the quark mixing matrix $V_{CKM}$. It is assumed from a phenomenological point of view that the neutrino Dirac mass matrix $M_D$ is given with a somewhat different structure from the charged lepton mass matrix $M_e$, although $M_D=M_e$ was assumed in the previous model. As a result, the revised model predicts a reasonable value ${\sin }^{2}2{\theta }_{13}\sim 0.07$ with keeping successful results for other parameters in $U_{PMNS}$ as well as $V_{CKM}$ and quark and lepton mass ratios.