The Majoron model and stellar collapse

Stellar core collapse is studied with the Gelmini-Roncadelli-Georgi-Glashow-Nussinov Majoron model of the weak interaction. The large-scale lepton number nonconservation in neutrino-neutrino interactions, which is inherent in this model, leads to entropy production in the infall epoch of the presupernova star and a thermal bounce of the core at subnuclear density. This result is quite different from the standard low-entropy model of stellar collapse and occurs for values of the dimensionless coupling constant, g, characterizing the Majoron model, g = 3x10 to the -5th or larger. Three different scenarios for the thermalization of neutrinos and majorons are considered. In the case where total neutrino plus majoron number is not conserved, it is found that the spectrum of neutrinos resulting after core bounce may be inconsistent with the observed neutrino spectrum from SN 1987A whenever g = 3x10 to the -4th or larger.