Nonunitary neutrino mixing in short and long-baseline experiments

Nonunitary neutrino mixing in the light neutrino sector is a direct consequence of type-I seesaw neutrino mass models. In these models, light neutrino mixing is described by a submatrix of the full lepton mixing matrix and, then, it is not unitary in general. In consequence, neutrino oscillations are characterized by additional parameters, including new sources of CP violation. Here we perform a combined analysis of short and long-baseline neutrino oscillation data in this extended mixing scenario. We did not find a significant deviation from unitary mixing, and the complementary data sets have been used to constrain the nonunitarity parameters. We have also found that the T2K and NOvA tension in the determination of the Dirac CP-phase is not alleviated in the context of nonunitary neutrino mixing.

Automated summary

Nonunitary neutrino mixing in the light neutrino sector can lead to new sources of CP violation and requires additional parameters to describe neutrino oscillations, yet no significant deviation from unitary mixing was observed in experimental data. By combining different data sets, constraints on nonunitarity parameters were obtained, and tension between T2K and NOvA in determining the Dirac CP-phase was observed.