Non-unitary leptonic flavor mixing and CP violation in neutrino-antineutrino oscillations

Abstract If massive neutrinos are Majorana particles, then the lepton number should be violated in nature and neutrino-antineutrino oscillations ν α ↔ ν ‾ β (for α , β = e , μ , τ ) will definitely take place. In the present paper, we study the properties of CP violation in neutrino-antineutrino oscillations with the non-unitary leptonic flavor mixing matrix, which is actually a natural prediction in the canonical seesaw model due to the mixing between light and heavy Majorana neutrinos. The oscillation probabilities P ( ν α → ν ‾ β ) and P ( ν ‾ α → ν β ) are derived, and the CP asymmetries A α β ≡ [ P ( ν α → ν ‾ β ) − P ( ν ‾ α → ν β ) ] / [ P ( ν α → ν ‾ β ) + P ( ν ‾ α → ν β ) ] are also calculated. Taking into account current experimental bounds on the leptonic unitarity violation, we show that the CP asymmetries induced by the non-unitary mixing parameters can significantly deviate from those in the limit of a unitary leptonic flavor mixing.