The six known types of leptons are shown in the table below. There are also six anti-lepton types, one for each lepton. The electron is the least massive charged particle of any type. It is absolutely stable because conservation of energy and electric charge together forbid any decay . The antiparticle of the electron is called a positron .
Positrons are also stable particles.
However, positrons can annihilate when they meet an electron. Both the electron and the positron vanish, and their energy goes into photons and, possibly, more massive particles. Muons are produced in particle physics experiments. They also are produced by cosmic rays . Because they are much more massive than electrons, muons readily pass through the electric fields inside matter with very little deflection.