A Review of Searches for Evidence of Tachyons

Here, we review searches for empirical evidence for the existence of tachyons, superluminal particles having m2<0. The review considers searches for new particles that might be tachyons, as well as evidence that neutrinos are tachyons from data that may have been gathered for other purposes. Much of the second half of the paper is devoted to the 3+3 neutrino model including a tachyonic mass state, which has empirical support from a variety of areas. Although this is primarily a review article, it contains several newly identified results.