What is "negative muon"

lepton \lepton\ n. (Physics) an elementary particle that participates in weak interactions but does not participate in the strong interaction; it has a baryon number of 0. Some known leptons are the electron, the negative muon, the tau-minus particle, and the neutrinos associated with each of these particles.

n. an elementary particle with a negative charge and a half-life of 2 microsecond; decays to electron and neutrino and antineutrino [syn: muon, mu-meson]