Effective Majorana Neutrino Mass for ΔL=2 Neutrino Oscillations

It is well known that the observations of neutrinoless double-beta decay prove the Majorana nature of the neutrino. However, with specific values of Majorana phases, the effective Majorana neutrino mass to be estimated from the observation of neutrinoless double-beta decay experiments is strongly suppressed if the neutrino mass pattern adheres to a normal ordering. In this case, double-beta decay might not be observed even though the neutrino is Majorana in nature. We show if neutrinos oscillate to antineutrinos in their propagation; then, the observation of this oscillation proves that neutrinos are Majorana and will provide a measurement of neutrino masses and Majorana phases.