Nucleon-resonance transitions in neutrinoless double-βdecay and Majorana neutrinos

The role of nucleon resonances in neutrinoless nuclear double-$\beta$ decay is reexamined. It is found that a generalization of the $N^{*}$ mechanism may be operative. If so, earlier results are justified, and the limit of $m_N>{10}^4$ GeV is essentially unaltered for a heavy Majorana neutrino with full-strength left or right coupling to electrons and quarks.