Positron lepton number9/20/2023 ![]() This provides a lepton number of -1, balancing the final state and giving the final reaction: n -> p + e - + ν eīoth of these examples have the initial lepton number equal to 0, that is, they're hadron decays. ![]() A positron would destroy conservation of charge, so an antineutrino, ν e, is the only option. This electron provides a lepton number of +1 to the final state, and since the initial state has lepton number 0, this requires an antilepton in the final state. Conservation of charge requires that an electron also be produced, so that the final state is electrically neutral. So lepton number conservation dictates that pion decay proceeds by the reaction:Ī free neutron will decay into a proton after an average lifetime of about 900 seconds. Rather, we must add a muon neutrino, ν μ, to the final state so that the lepton number of the final state is also zero. Thus the reaction π + -> μ + never occurs. However, while an antimuon has lepton number -1, a pion has zero muon number. When a positive pion, π +, decays, it generally (99.99% of the time) decays into an antimuon, μ +. Two illustrative examples of conservation of lepton number are the decay of the pion and the decay of the neutron. Conservation of lepton number often prescribes the production of neutrinos and antineutrinos, since they have no charge and thus do not disturb the conservation of charge in an interaction. This has a significant effect on the nature of particle interactions and decays. All other Standard Model particles have lepton number 0.Ĭonservation of lepton number is obeyed by all known interactions, i.e. ![]() All of these particles have lepton number +1, and their antiparticles have lepton number -1. As would be expected, this quantity is associated with the class of elementary particles called leptons: the electron, muon, and tau particles, and their corresponding neutrinos. Lepton number is a conserved quantity in fundamental particle physics. ![]()
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