Non-unitary neutrino mixing in short and long-baseline experiments

TL;DR

This paper investigates the effects of non-unitary neutrino mixing, arising from type-I seesaw models, on short and long-baseline neutrino oscillation experiments, constraining non-unitarity parameters and examining CP violation.

Contribution

It provides a combined analysis of experimental data to constrain non-unitary neutrino mixing parameters and assesses its impact on CP violation and experimental tensions.

Findings

No significant deviation from unitary mixing was observed.

Non-unitarity parameters are constrained by the data.

The T2K and NOvA tension remains unresolved in this scenario.

Abstract

Non-unitary 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 sub-matrix 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 non-unitarity 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 non-unitary neutrino mixing.