$\rho$ exchange contribution to neutrinoless double beta decay

Abstract

We consider $\rho$ meson contributions to neutrinoless double beta decay amplitude stemming from the hadronization of the short distance quark-electron currents. These contributions are evaluated within vacuum dominance approximation. The one and two $\rho$ exchange contributions affect the Fermi transition nuclear matrix element in a way that lead to near cancellations in the same chirality, left-left and right-right, short range amplitudes when these new contributions are combined with the conventional short range amplitudes, while the left-right amplitude almost triples. This then necessitates the inclusion of $\rho$ exchange amplitudes in any phenomenological study, like in left-right theories.