Testing non-unitarity of neutrino mixing matrices at neutrino factories

Understand

In this paper we explore the effect of non-unitary neutrino mixing on neutrino oscillation probabilities both in vacuum and matter.

• In particular, we consider the $\nu_\mu \to \nu_\tau$ channel and using a Neutrino Factory as the source for $\nu_\mu$'s discuss the constraints that can be obtained on the moduli and phases of the parameters characterizing the violation of unitarity.
• We point out how the new CP violation phases present in the case where the non-unitary mixings give rise to spurious ``degenerate'' solutions in the parameter space and discuss how the true solutions can be extricated by combining measurements at several baselines.