The muon (from the Greek letter mu (μ) used to represent it)'s an elementary particle similar to the electron, with negative electric charge and a spin of . Together with the electron, the tauon, and the three neutrinos, it's classified as a lepton. It's the unstable subatomic particle with the second longest mean lifetime, behind the neutron (~). Like all elementary particles, the muon has corresponding antiparticle of opposite charge but equal mass and spin: the antimuon (also called a p… (More on Muon)