Theoretical bounds for majoron emission from nuclear double-beta decay processes

Theoretical upper limits for the neutrino-majoron coupling constant, g, are extracted from a systematic calculation of neutrinoless double-beta decay rates for transitions in ⁴⁸Ca, ⁷⁶Ge, ⁸²Se, ¹²⁸Te, ¹³⁰Te and ¹³⁶Xe. The nuclear wavefunctions which we have used to compute the theoretical bounds on g have been tested in calculations involving two-neutrino and neutrinoless double-beta decay rates. The resulting value is of the order of g approximately=10^-4, in good agreement with recently reported data by the Heidelberg-Moscow-LNGS collaboration.