  We study the effective operators of the standard model fields which would
yield an observable rate of neutrinoless double beta decay. We particularly
focus on the possibility that neutrinoless double beta decay is dominantly
induced by lepton-number-violating higher dimensional operators other than the
Majorana neutrino mass. Our analysis can be applied to models in which
neutrinoless double beta decay is induced either by a strong dynamics or by
quantum gravity effects at a fundamental scale near the TeV scale as well as
the conventional models in which neutrinoless double beta decay is induced by
perturbative renormalizable interactions.
