The Tau lepton (or tauon) is a negatively charged elementary particle with a high mass of 1777 MeV. It is associated with an antiparticle and a neutrino. It is a 3rd generation of matter particle, and quickly decays to a stable 1st generation (normal matter) particle. Due to approximate tauon number conservation (neutrino oscillations violate this "conservation" law) (lepton number conservation), a tau neutrino is created when a tauon decays to a lighter lepton (muon or electron). Except for its high mass and its instability, a tauon otherwise resembles an electron.
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