Search

Recently, the reactor mixing angle ${\theta }_{13}$ has been measured precisely by Daya Bay, RENO, and T2K experiments with a moderately large value. However, the standard form of neutrino mixing patterns such as bimaximal, tri-bimaximal, golden ratio of types A and B, hexagonal, etc., which are based on certain flavor symmetries, predict vanishing ${\theta }_{13}$ . Using the fact that the neutrino mixing matrix can be represented as ${V}_{\mathrm{PMNS}}={U}_{l}^{\dagger }{U}_{\nu }{P}_{\nu }$ , where U _l and ${U}_{\nu }$ result from the diagonalization of the charged lepton and neutrino mass matrices and ${P}_{\nu }$ is a diagonal matrix containing Majorana phases, we explore the possibility of accounting for the large reactor mixing angle by considering deviations both in the charged lepton and neutrino sector. In the charged lepton sector we consider the deviation as an additional rotation in the (12) and (13) planes, whereas in the neutrino sector we consider deviations to various neutrino mixing patterns through (13) and (23) rotations. We find that with the inclusion of these deviations it is possible to accommodate the observed large reactor mixing angle ${\theta }_{13}$ , and one can also obtain limits on the charge-conjugation parity-violating Dirac phase ${\delta }_{{CP}}$ and Jarlskog invariant J _CP for most of the cases. We then explore whether our findings can be tested in the currently running NuMI Off-axis v _e Appearance experiment with three years of data taking in neutrino mode followed by three years with the anti-neutrino mode.

In this paper, we consider the low energy scale inverse seesaw mechanism in which the observed neutrino mass and lepton mixing are explained by introducing right-handed neutrinos and the gauge-singlet fermions with experimentally testable energy scale. Moreover, the presence of such new fermions leads to unitarity violation in lepton mixing due to significantly large mixing between active neutrinos and the heavy fermions. In addition to this, such large lepton mixing also gives rise to potentially large lepton flavor violation, which allows one to constrain the non-unitarity parameters via lepton flavor violating decays (li → ljγ). We make use of these constraints on non-unitarity parameters and investigate their effects on the determination of current unknown oscillation parameters at long-baseline experiments. We find that non-unitarity parameters are sensitive to the NOνA experiment. However, it is observed that the NOνA experiment is not expected to improve the current knowledge of non-unitarity parameter η21. We also find that the sensitivities to current unknowns are deteriorated significantly in the presence of non-unitary lepton mixing and these sensitivities crucially depend upon the new CP-violating phase in the non-unitary mixing. Further, we find that the degeneracy resolution capability of the NOνA experiment is reduced in the presence of non-unitarity parameters. However, the synergy between the currently running experiments T2K and NOνA can improve the parameter degeneracy resolution and hence there is enhancement in the sensitivities of unknowns. [ABSTRACT FROM AUTHOR]