Non-unitary leptonic mixing and CP-violation

Some theories of new physics accounting for neutrino masses can give rise to a low-energy non-unitary leptonic mixing matrix. It is shown that the CP-asymmetries in the $\nu_\mu\to \nu_\tau$ channel are an excellent probe of such new physics. In adition, we clarify the relationship betweeen our framework and the so called "non-standard neutrino interactions" scenarios: the sensitivities explored here apply as well to such constructions, except for extremely fine-tuned cancellations.