Charged lepton contributions to bimaximal and tri-bimaximal mixings for generating $\sin {\theta }_{13}\ne 0$ and ${\tan }^2{\theta }_{23}<1$

Abstract

Bimaximal (BM) and tri-bimaximal (TB) mixings of neutrinos are two special cases of lepton mixing matrix, which predict the reactor angle ${\theta }_{13}=0$ and the atmospheric angle ${\tan }^2{\theta }_{23}=1$. Recent precision measurements and global analysis of oscillation parameters, have confirmed a non-vanishing value of ${\theta }_{13}$ as well as deviations of ${\theta }_{12}$ and ${\theta }_{23}$ from their maximal values predicted by BM or TB mixing. In this work we mainly concentrate on ${\theta }_{13}$ and ${\theta }_{23}$ to assign $\sin {\theta }_{13}\ne 0$ and ${\tan }^2{\theta }_{23}<1$ with the help of charged lepton corrections defined by $U_{PMNS}=U_l^{†}{U}_{\nu }$. We first consider $U_{\nu }$ to be given separately by BM and TB mixing matrices and then find the possible forms of U_l} such that the elements of PMNS matrix, finally yield $\sin {\theta }_{13}\ne 0$ and ${\tan }^2{\theta }_{23}<1$. To compute the values of mixing angles we assume the charged lepton correction to be of CKM-like. All the mixing matrices considered here satisfy the unitarity condition to leading order of expansion parameters. We also analyze both the mixing schemes in presence of Dirac CP phase and find expressions for the rephasing invariant quantity $J_{CP}$ which have been discussed in recent literature.

Comments: 16 pages, four figures, revised version, accepted in Physics Letter B