 In the context of light Majorana neutrino exchange, "m"ββ is given by

where "mi" are the neutrino masses and the "Uei" are elements of the Pontecorvo–Maki–Nakagawa–Sakata (PMNS) matrix.Therefore, observing neutrinoless double beta decay, in addition to confirming the Majorana neutrino nature, can give information on the absolute neutrino mass scale and Majorana phases in the PMNS matrix, subject to interpretation through theoretical models of the nucleus, which determine the nuclear matrix elements, and models of the decay.The observation of neutrinoless double beta decay would require that at least one neutrino is a Majorana particle, irrespective of whether the process is engendered by neutrino exchange.