tau

A tau is a type (i.e., flavor) of lepton that has an electric charge of -1, like an electron, but far more mass (more than 3000 times more, and 17 times more than a muon) and is unstable, decaying with a lifetime that is less than a picosecond. They result from high-energy particle interactions, and decay into a tau neutrino plus one or more pions. Such interactions happen naturally, e.g., the interactions of neutrinos passing through Earth as well as within its atmosphere. Analysis of air showers take this into account.