Universality of Quark-Lepton Mass Matrix

The recently observed lepton mixing angle $\theta_{13}$ of the MNS mixing matrix is well incorporated in a universal mixing hypothesis between quark and lepton sectors. This hypothesis asserts that, in the charged lepton diagonal base, all other mass matrices for up- and down-type quarks and light neutrinos are diagonalized by the same unitary matrix except for the phase elements. It is expressed as $V_{CKM}= U_{MNS}(\delta^\prime)^\dagger P U_{MNS}(\delta)$ for quark mixing matrix $V_{CKM}$ and lepton mixing matrix $U_{MNS}(\delta)$ in the phenomenological level. Here $P$ is a diagonal phase mass matrix. $\delta^\prime$ is a slightly different phase parameter from the Dirac CP violating phase $\delta=1.1\pi$ (best fit) in the MNS lepton mixing matrix.Comment: 6 pages, 2 figures, accepted by MPL

Maximal CP Violation Hypothesis and a Lepton Mixing Matrix

Maximal CP violation hypothesis is applied to a simple lepton mixing matrix form U=V_{CKM}^\dagger U_{TB}, which has recently been speculated under an ansatz that U becomes an exact tribimaximal mixing U_{TB} in a limit of the quark mixing matrix V_{CKM} \to {\bf 1}. The prediction \tan^2 \theta_{12} =1/2 in the case of the exact tribimaximal mixing U=U_{TB} is onsiderably spoiled in the speculated mixing U=V_{CKM}^\dagger U_{TB}. However, the application of the hypothesis to the lepton sector can again recover the spoiled value to \tan^2 \theta_{12} \simeq 1/2 if the original Kobayashi-Maskawa phase convention for V_{CKM} is adopted.Comment: 10 pages, 4 figure, version in Phys.Rev.