5 Reasons to expect an 8 MeV line in the SN 1987A neutrino spectrum

Abstract

Evidence was previously reported for an 8 MeV neutrino line associated with SN 1987A based on an analysis of 997 events recorded in the Kamiokande-II detector on the day of the supernova. That claimed line, however, occurred at the peak of the background spectrum, and both had a similar shape, making the claim tenuous at best. Here the claim is buttressed by providing five reasons to expect such an 8 MeV neutrino line. A final section of the paper concerns the ongoing KATRIN experiment to find the neutrino mass, which might provide additional support for the line, should it validate a controversial 3 + 3 model of the neutrino masses, including a tachyonic (m2 < 0) mass.