Constraining the absolute neutrino mass scale and Majorana CP violating phases by future 0νββ decay experiments -: art. no. 093010

Assuming that neutrinos are Majorana particles, in a three-generation framework, current and future neutrino oscillation experiments can determine six out of the nine parameters which fully describe the structure of the neutrino mass matrix. We try to clarify the interplay among the remaining parameters, the absolute neutrino mass scale and two CP violating Majorana phases, and how they can be accessed by future neutrinoless double beta (0nubetabeta) decay experiments, for the normal as well as for the inverted order of the neutrino mass spectrum. Assuming the oscillation parameters to be in the range presently allowed by atmospheric, solar, reactor, and accelerator neutrino experiments, we quantitatively estimate the bounds on m(0), the lightest neutrino mass, that can be inferred if the next generation 0nubetabeta decay experiments can probe the effective Majorana mass (m(ee)) down to similar to1 meV. In this context we conclude that in the case that neutrinos are Majorana particles, (a) if m(0)greater than or similar to300 meV, i.e., within the range directly attainable by future laboratory experiments as well as astrophysical observations, then m(ee)greater than or similar to30 meV must be observed, (b) if m(0)<300 meV, results from future 0nubetabeta decay experiments combined with stringent bounds on the neutrino oscillation parameters, especially the solar ones, will place much stronger limits on the allowed values of m(0) than these direct experiments. For instance, if a positive signal is observed around m(ee)=10 meV, we estimate 3less than or similar tom(0)/meVless than or similar to65 at 95% C.L.; on the other hand, if no signal is observed down to m(ee)=10 meV, then m(0)less than or similar to55 meV at 95% C.L.