B-L-violation in Softly Broken Supersymmetry and Neutrinoless Double Beta Decay

We prove a low-energy theorem valid for any model of weak scale softly broken supersymmetry. It claims that the neutrino Majorana mass, the B-L violating mass of the sneutrino and the neutrinoless double beta decay amplitude are intimately related to each other such that if one of them is non-zero the other two are also non-zero and, vice versa, if one of them vanishes the other two vanish as well. The theorem is a consequence of the underlying supersymmetry and independent of the mechanisms of neutrinoless double beta decay and (s-)neutrino mass generation.