УСПЕХИ ФИЗИЧЕСКИХ НАУКСОВЕЩАНИЯ И КОНФЕРЕНЦИИ 53(048) НАУЧНАЯ СЕССИЯ ОТДЕЛЕНИЯ ОБЩЕЙ ФИЗИКИ И АСТРОНОМИИ И ОТДЕЛЕНИЯ ЯДЕРНОЙ ФИЗИКИ АКАДЕМИИ НАУК СССР (26-27 марта 1986 г.) 26 и 27 марта 1986 г. в Институте физических проблем им.С. И. Вавилова АН СССР

The present state of the problem of the double neutrinoless beta decay, 2β(0ν), and related questions is reviewed. Various mechanisms for ΔL = 2 transitions in models with spontaneous violation of lepton number (L) conservation are discussed. From the standpoint of unified gauge theories, a Majorana neutrino mass would be the most probable reason for processes with ΔL = 2 (if they occur). The 2β(0ν) decay is compared with other phenomena which are sensitive to the neutrino mass. It follows from this comparison that the 2β(0ν) decay is essentially the only process which could be detected at the present level of experimental capabilities and which might tell us about the nature of the neutrino mass, if this mass is some tens of electron volts.