Tau neutrino

The tau neutrino or tauon neutrino is an elementary particle which has the symbol ν
_τ and zero electric charge. Together with the tau (τ), it forms the third generation of leptons, hence the name tau neutrino. Its existence was immediately implied after the tau particle was detected in a series of experiments between 1974 and 1977 by Martin Lewis Perl with his colleagues at the SLAC–LBL group.^[1] The discovery of the tau neutrino was announced in July 2000 by the DONUT collaboration (Direct Observation of the Nu Tau).^[2][3] In 2024, the IceCube Neutrino Observatory published findings of seven astrophysical tau neutrino candidates.^[4][5]

As of 2022 they have been called the "least studied particle in the standard model" because of their low cross section, difficulty of production, and difficulty to distinguish from other neutrino flavors.^[6] One review argues they are worth studying more in order to finally completely measure their properties, test our knowledge of neutrino mixing, probe possible anomalies, and make full use of experiments that are sensitive to tau neutrinos in any case.^[6]