摘要：This paper introduces the neutrinoless double-beta decay (the rarest nuclear weak process) and
describes the status of the research for this transition, both from the point of view of theoretical
nuclear physics and in terms of the present and future experimental scenarios. Implications of this
phenomenon on crucial aspects of particle physics are briefly discussed. The calculations of the nuclear
matrix elements in case of mass mechanisms are reviewed, and a range for these quantities is proposed
for the most appealing candidates. After introducing general experimental concepts—such as the
choice of the best candidates, the different proposed technological approaches, and the sensitivity—we make the point on the experimental situation. Searches running or in preparation are described, providing an organic presentation which picks up similarities and differences. A critical comparison of
the adopted technologies and of their physics reach (in terms of sensitivity to the effective Majorana
neutrino mass) is performed. As a conclusion, we try to envisage what we expect round the corner
and at a longer time scale.
