NEUTRINOLESS DOUBLE-BETA DECAY WITH COMPOSITE NEUTRINOS

We study in detail the contribution of heavy composite Majorana neutri nos to neutrinoless double beta decay (0 nu beta beta). Our analysis c onfirms the result of a previous estimate by two of the authors. Excit ed neutrinos couple to the electroweak gauge bosons through a magnetic -type effective Lagrangian. The relevant nuclear matrix element is rel ated to matrix elements available in the literature and current bounds on the half-life of 0 nu beta beta are converted into bounds on the c ompositeness scale and/or the heavy neutrino mass. Our bounds are of t he same order of magnitude as those available from accelerator experim ents.