Tri-bimaximal-Cabibbo Mixing

Abstract

Recent measurements of the lepton mixing angle $\theta_{13}$ by the Daya Bay and RENO reactor experiments are consistent with the relationship $\theta_{13}\approx \theta_C/\sqrt{2}$ where $ \theta_C$ is the Cabibbo angle. We propose Tri-bimaximal-Cabibbo (TBC) mixing, in which $\sin \theta_{13}= \sin \theta_C/\sqrt{2}$, $\sin \theta_{23}= 1/\sqrt{2}$ and $\sin \theta_{12}= 1/\sqrt{3}$. We show that TBC mixing may arise approximately from Tri-bimaximal, Bi-maximal or Golden Ratio neutrino mixing, together with Cabibbo-like charged lepton corrections arising from a Pati-Salam gauge group, leading to predictions for the CP-violating phase of $\delta \approx \pm 90^o, \pm 180^o, \pm 75^o$, respectively. Alternatively, we show that TBC neutrino mixing may realised accurately using the type I see-saw mechanism with partially constrained sequential right-handed neutrino dominance, assuming a family symmetry which is broken by a flavon common to quarks and neutrinos.