A tau neutrino is one of the three known flavours of neutrino. Neutrinos are low mass neutral leptons described by the electroweak theory. These fermions, although sensitive to gravity, can only interact with quarks and other particles in the standard model through the weak nuclear force. They exist in three forms, or flavours, and can be transformed into each other by the oscillationmechanism postulated by the physicist Bruno Pontecorvo. These neutrino oscillations were finally revealed by the Super-kamiokande detector.
The formation of tau neutrinos
Neutrinos are produced and absorbed during high energy nuclear reactions, for example in the nucleosynthesis reactions that make the stars and the Sunshine. In this case, however, it is electron neutrinos that appear. Tau neutrinos appear in reactions with tauons, a heavier relation of the electron. The tauon was discovered by Martin Perl but the tao neutrino was only observed in 2000 at the Fermilab in the DONUT experiment.
The Nobel physics prize winner Martin Perl, discoverer of the tauon, heavier relation of the electron. © Peter Ginter