An unsuccessful search for fractionally charged particles with mass ≲2.2 GeV

Abstract

According to conventional wisdom the 5 h early Mont Blanc burst probably was not associated with SN 1987A, but if it was genuine, some exotic physics explanation had to be responsible. Here we consider one truly exotic explanation, namely faster-than-light neutrinos having mν2=−0.38 keV2. It is shown that the Mont Blanc burst is consistent with the distinctive signature of that explanation i.e., an 8 MeV antineutrino line from SN 1987A. It is further shown that a model of core collapse supernovae involving dark matter particles of mass 8 MeV would in fact yield an 8 MeV antineutrino line. Moreover, that dark matter model predicts 8 MeV ν,ν¯ and e+e− pairs from the galactic center, a place where one would expect large amounts of dark matter to collect. The resulting e+ would create γ−rays from the galactic center, and a fit to MeV γ−ray data yields the model’s dark matter mass, as well as the calculated source temperature and angular size. These good fits give indirect experimental support for the existence of an 8 MeV antineutrino line from SN 1987A. More direct support comes from the spectrum of N ∼ 1000 events recorded by the Kamiokande-II detector on the day of SN 1987A, which appear to show an 8 MeV line atop the detector background. This ν¯ line, if genuine, has been well-hidden for 30 years because it occurs very close to the peak of the background. This fact might ordinarily justify extreme skepticism. In the present case, however, a more positive view is called for based on (a) the very high statistical significance of the result (30σ), (b) the use of a detector background independent of the SN 1987A data using a later K-II data set, and (c) the observation of an excess above the background spectrum whose central energy and width both agree with that of an 8 MeV ν¯ line broadened by 25% resolution. Most importantly, the last observation is in accord with the prior prediction of an 8 MeV ν¯ line based on the Mont Blanc data, and the dark matter model, itself supported by experimental observations. Lastly, it is noted that the tachyonic interpretation of the Mont Blanc burst fits the author’s earlier unconventional 3+3 model of the neutrino mass states. Experimental corroboration should be sought for the linked hypotheses of an 8 MeV ν¯ line or an mν2=−0.38 keV2. The former might be seen in existing astrophysical data, while the latter should be proven or refuted by the KATRIN experiment in a short data-taking period.