Constraints from Nucleosynthesis and SN1987A on Majoron Emitting Double Beta Decay

We examine whether observable majoron emission in double beta decay can be compatible with the big-bang nucleosynthesis (NS) and the observed neutrino flux from SN1987A. It is found that the NS upper bound on $^4$He abundance implies that the majoron-neutrino Yukawa coupling constant $g\leq 9\times 10^{-6}$ and its maximal value is allowed only when the scalar quartic coupling constant $\lambda$ is extremely small, $\lambda\leq 100g^2$. It is also observed that, although quite less restrictive, SN1987A also provides independent constraints on coupling constants.