Tau (particle) Tau (particle) The tau (τ), also called the tau lepton, tau particle, or tauon, is an elementary particle similar to the electron, with negative electric charge and a spin of. Together with the electron, the muon, and the three neutrinos, it is a lepton. Like all elementary particles with half-integer spin, the tau has a corresponding antiparticle of opposite charge but equal mass and spin, which in the tau's case is the antitau (also called the "positive tau"). Tau particles are denoted by and the antitau by . Tau leptons have a lifetime of and a mass of (compared to
Kelsey (given name) in 1996. It was the 528th most common name for women in the United States in the 1990 census. Kelsey was ranked among the top 100 names for girls born in Scotland in 2007. It was also among the top 100 names for girls born in England and Wales in the late 1990s. People with the given name Kelsey: Kelsey (given name) Kelsey Is a unisex given name of English origin. The name most probably derives from an Old English given name "Ceolsige", which meant "ship's victory", or it could be a place name meaning "Cenel's island". "Cenel's Island" is