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August 3, 2021

The first results from the KATRIN experiment in 2019 were consistent with both the existence of a single effective mass neutrino of mass under 1.1 eV, and also an exotic “3+3” neutrino model that had been proposed in 2013. This model assumes three active-sterile pairs, having specific masses, one of which is imaginary. This short paper shows how the experiment’s first results are consistent with that model. In June 2021 KATRIN published new results from a second run which lowered the value of the electron neutrino mass further to m < 0.7 eV. Again. however, those results may again be consistent with the controversial 3 + 3 model as shown here. A definitive test of the 3 + 3 model should be possible as KATRIN acquires more data, but such a test has not been carried out at the time of this writing.

Photo shows the interior of the KATRIN main spectrometer Credit: Michael Zacher. A 27 min video about the experiment can be found here.