Last update Dec 15, 2022
Overall situation. A review of the situation foe experimental searches for tachyons and for evidence that neutrinos are tachyons was published in 2022. See: R, Ehrlich, A Review of Searches for Evidence of Tachyons, Symmetry 2022, 14(6), 1198, Symmetry | Free Full-Text | A Review of Searches for Evidence of Tachyons | HTML (mdpi.com)
KATRIN experiment. Concerning ongoing experiments that might provide evidence that neutrinos are tachyons, the most important of these is the KATRIN experiment which has been taking data since 2019. 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. Hopefully, such a test will eventually be carried out. The most recent review of evidence for the 3 + 3 model, and tachyon searches in general can be found in the reference given in the first paragraph.
Project 8. Is an experiment that promises to yield even better resolution for the neutrino mass than KATRIN, but as of 2023 it is just beginning to take data using Cyclotron Radiation Emission Spectroscopy, as described here.
Supernovae. A more direct test of the 3 + 3 model would be provided if there were a galactic supernova, but these occur only two or three times per century, Currently only upper limits exist for neutrinos from extragalactic supernovae. Nevertheless it is possible that existing detectors, including Super-Kamiokande, might observe one with a different “search window time” as suggested in R. Ehrlich, 5 Reasons to expect an 8 MeV line in the SN 1987A neutrino spectrum, Lett. in High En. Phys., LHEP-199, 2021 https://arxiv.org/pdf/2101.08128.pdf
Photo shows the interior of the KATRIN main spectrometer Credit: Michael Zacher. A 27 min video about the experiment can be found here.