Short-baseline neutrino oscillations and neutrinoless double- beta decay in the framework of three neutrino mixing and a mass hierarchy.

We have analyzed the results of the latest terrestrial neutrino oscillation experiments in the framework of a model with mixing of three massive neutrinos and a neutrino mass hierarchy ({ital m}{sub 1}{lt}{ital m}{sub 2}{lt}{ital m}{sub 3}). In this model, oscillations of the terrestrial neutrinos are characterized by three parameters, {Delta}{ital m}{sup 2}{equivalent_to}{ital m}{sup 2}{sub 3}{minus}{ital m}{sup 2}{sub 1} and the squared moduli of the two mixing matrix elements {ital U}{sub {ital e}3} and {ital U}{sub {mu}3}. Using the results of disappearance experiments and solar neutrino experiments, it is shown that only two regions of possible values of {vert_bar}{ital U}{sub {ital e}3}{vert_bar}{sup 2} and {vert_bar}{ital U}{sub {mu}3}{vert_bar}{sup 2} are allowed: (I) {vert_bar}{ital U}{sub {ital e}3}{vert_bar}{sup 2} and {vert_bar}{ital U}{sub {mu}3}{vert_bar}{sup 2} are both small and (II) {vert_bar}{ital U}{sub {ital e}3}{vert_bar}{sup 2} is small and {vert_bar}{ital U}{sub {mu}3}{vert_bar}{sup 2} is large. If the mixing parameters are in region I, {nu}{sub {mu}}{sq_bullet}{nu}{sub {ital e}} oscillations are suppressed. In this case the LSND indication in favor of {nu}{sub {mu}}{sq_bullet}{nu}{sub {ital e}} oscillations is not compatible with the negative results of all other experiments. If the mixing parameters are in region II, {nu}{sub {ital e}}{sq_bullet}{nu}{sub {tau}} oscillations are strongly suppressed. If massive neutrinos are Majoranamore » particles, our analysis shows that neutrinoless double-{beta} decay could be observed in the experiments of the next generation only if the mixing parameters are in region I. {copyright} {ital 1996 The American Physical Society.}« less