One 17-keV Majorana neutrino?

We present a model accommodating a 17-keV neutrino with 1% mixing with the electron neutrino and bounds on the electron-neutrino mass and neutrinoless double-β decay. However, in contrast to previous models, there is only a single state with mass 17 keV. This model is consistent with cosmological and supernova-cooling constraints, and incorporates the Mikheyev-Smirnov-Wolfenstein explanation of the low solar-neutrino counts. Possible signatures of our model include an excess of muon neutrinos from a supernova explosion, spread over a period of 10--1000 sec, and a Higgs-boson decay signature of leptons plus missing energy