Pseudo-Dirac Neutrinos: A Challenge for Neutrino Telescopes

Abstract

Neutrinos may be pseudo-Dirac states, such that each generation is actually composed of two maximally mixed Majorana neutrinos separated by a tiny mass difference. The usual active neutrino oscillation phenomenology would be unaltered if the pseudo-Dirac splittings are [Formula presented]; in addition, neutrinoless double beta decay would be highly suppressed. However, it may be possible to distinguish pseudo-Dirac from Dirac neutrinos using high-energy astrophysical neutrinos. By measuring flavor ratios as a function of [Formula presented], mass-squared differences down to [Formula presented] can be reached. We comment on the possibility of probing cosmological parameters with neutrinos. © ..