Constraints on Composite-Models Effective Lagrangians from Neutrinoless Double Beta Decay

Abstract

We give a brief review of the existing bounds on effective couplings for excited states ($e^*, \nu^*, u^*, d^* $) of the ordinary quarks and leptons arising from a composite model scenario. We then explore the phenomenological implications of the hypothesis that the excited neutrino $\nu^*$ might be of Majorana type. Recent bounds on the half-life of the $\Delta L =2 $ neutrinoless double beta decay ($0\nu\beta\beta $) are used to constraint the compositeness effective couplings. We show that the bounds so obtained are roughly of the same order of magnitude as those available from high energy experiments.