Double beta decay has been proven to be a powerful tool to constrain B−L
violating physics beyond the standard model. We present a representation for
the long-range part of the general 0νββ decay rate allowed by
Lorentz-invariance. Combined with the short range part this general
parametrization in terms of effective B−L violating couplings will provide
the 0νββ limits on arbitrary lepton number violating theories.Comment: Talk presented by H. P\"as at the Erice School on Nuclear Physics,
19th course "Neutrinos in Astro, Particle and Nuclear Physics", Erice, Italy,
16-24 September 1997, 2 pages, Latex, requires worldsci.st