Limit on double beta decay with majoron emission

Abstract A search for majoron emission accompanying neutrinoles double beta decay in 76 Ge was conducted with a low background germanium detector in the St. Gotthard underground laboratory. No evidence for neutrinoless double beta decay with or without majoron emission was found, with a lower limit for the half life of the majoron branch of t 1 2 > 1.2 × 10 21 yr at 90% confidence level.