Cherenkov radiation

Taking the formalisms of electromagnetic radiation and supposing a tachyon had an electric charge—as there is no reason to suppose a priori that tachyons must be either neutral or charged—then a charged tachyon must lose energy as Cherenkov radiation^[15]—just as ordinary charged particles do when they exceed the local speed of light in a medium. A charged tachyon traveling in a vacuum therefore undergoes a constant proper time acceleration and, by necessity, its worldline forms a hyperbola in space-time. However, as we have seen, reducing a tachyon's energy increases its speed, so that the single hyperbola formed is of two oppositely charged tachyons with opposite momenta (same magnitude, opposite sign) which annihilate each other when they simultaneously reach infinite speed at the same place in space. (At infinite speed the two tachyons have no energy each and finite momentum of opposite direction, so no conservation laws are violated in their mutual annihilation. The time of annihilation is frame dependent.) Even an electrically neutral tachyon would be expected to lose energy via gravitational Cherenkov radiation, because it has a gravitational mass, and therefore increase in speed as it travels, as described above. See: Tachyon

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An early set of experiments with a facility called the solar neutrino telescope, measured the rate of neutrino emission from the sun at only one third of the expected flux. Often referred to as the Solar Neutrino Problem, this deficiency of neutrinos has been difficult to explain. Recent results from the Sudbury Neutrino Observatory suggest that a fraction of the electron neutrinos produced by the sun are transformed into muon neutrinos on the way to the earth. The observations at Sudbury are consistent with the solar models of neutrino flux assuming that this "neutrino oscillation" is responsible for observation of neutrinos other than electron neutrinos. See: Detection of Neutrinos