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^*, ν^*, 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 $ν^*$ might be of Majorana type. Recent bounds on the half-life of the $ΔL =2 $ neutrinoless double beta decay ($0νββ$) 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.