Supernova bounds on Majoron-emitting decays of light neutrinos

Abstract

Neutrino masses arising from the spontaneous violation of ungauged lepton-number are accompanied by a physical Goldstone boson, generically called a Majoron. In the high-density supernova medium the effects of Majoron-emitting neutrino decays are important even if they are suppressed in vacuo by small neutrino masses and/or small off-diagonal couplings. We reconsider the influence of these decays on the neutrino signal of supernovae in the light of recent Super-Kamiokande data on solar and atmospheric neutrinos. We find that Majoron-neutrino coupling constants in the range 3 x 10-7 ≤ g ≤ 2 x 10-5 or g ≤ 3 x 10-4 are excluded by the observation of SN 1987A. Then we discuss the potential of Super-Kamiokande and the Sudbury Neutrino Observatory to detect Majoron-neutrino interactions in the case of a future galactic supernova. We find that these experiments could probe Majoron-neutrino interactions with improved sensitivity. ©2000 The American Physical Society.