Bounds on the Coupling of the Majoron to Light Neutrinos from Supernova Cooling

We explore the role of Majoron (J) emission in the supernova cooling process, as a source of the upper bound on neutrino-Majoron coupling. We show that the strongest upper bound on the coupling to νe comes from the νeνe → J process in the core of a supernova. We also find bounds on diagonal couplings of the Majoron to νμ(τ)νμ(τ) and on off-diagonal νeνμ(τ) couplings in various regions of the parameter space. We discuss the evaluation of the cross-section for four-particle interactions (νν → JJ and νJ → νJ). We show that these are typically dominated by three-particle sub-processes and do not give new independent constraints.