A 2019 paper published in Advances in Astronomy, summarizes all the evidence found in support of one of the neutrinos being a tachyon prior to the KATRIN experiment.* An updated (and corrected) summary can be found in this 2022 paper, This evidence relies on analyses of previously published data, coming from fields including cosmic ray physics, particle physics and astrophysics. It also includes one theoretical argument, involving a new dark matter model of supernova SN 1987A. Although these papers will not be intelligible to most non-physicists, there is a tachyon powerpoint presentation that is intended for everyone. Most of the other links on the home page should also be intelligible to non-physicists, particularly “my tachyon prediction“ and the book “Hunting the Tachyon.” The KATRIN experiment now underway in Germany should by its conclusion have enough data to provide definitive evidence for or against the 3 + 3 model of the neutrino masses. This model, which was proposed in a 2013 paper, calls for one of the neutrinos being a tachyon having a specific imaginary mass. The first results of KATRIN published in September 2019 are consistent with both the conventional neutrino mass model and the 3 + 3 model as are those published in 2022.
*One piece of evidence presented, however, was a mistake as spelled out in this paper.