Determining the PMNS Matrix Elements without Assuming Unitarity

We analyse constraints on the elements of the PMNS matrix, the mixing matrix in the lepton sector, from present experimental data on neutrino oscillations as well as on electroweak decays. Without assuming unitarity of the PMNS matrix, neutrino oscillation experiments are only sensitive to half of the matrix elements. The combination with experimental data on electroweak decays allows to determine, or bound, all PMNS matrix elements. We compare our results to previous studies, where unitarity was assumed, and discuss prospects of future experiments for testing unitarity in the lepton sector.