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Classification of particles (Leptons (List of leptons: Electron Electron…
Classification of particles
Hadrons
Baryons
Examples: protons and neutrons
All baryons except protons are unstable. They decay into protons (although even protons are shown to be unstable, they have an extremely long half-life though so this is hard to show)
All baryons contain three quarks
There can be antibaryons, for example, antiprotons and antineutrons (but they are not found in ordinary matter)
Baryons have a baryon number of +1 and antibaryons have a baryon number of -1
Mesons
All mesons are unstable
All mesons contain a quark and an antiquark
Examples: pions and kaons
Pions and kaons were discovered in cosmic ray showers
There are antimesons
All hadrons are made of quarks
List of quarks:
Up
Down
Charm
Strange
Top
Bottom
and the antiquark for each
All quarks are unstable
Quarks can not be on their own
Hadrons feel a strong nuclear force (and the gravitational, electromagnetic and weak nuclear forces)
Hadrons are more massive than leptons. Baryons are the most massive hadrons and mesons are the least massive hadrons.
Leptons
List of leptons:
Electron
Electron-neutrino
Muon
Muon-neutrino
Tau
Tau-neutrino
and the antiparticle for each
Leptons are the lightest particle
Leptons feel a gravitational, electromagnetic and weak nuclear forces but not the strong nuclear force
The electron, electron-neutrino and the antiparticles for these (first generation) are the only leptons we find in ordinary matter
Muons and taus are unstable so they eventually decay into electrons
Neutrinos have no mass and no charge
There are 3 categories of lepton number:
L(e)
L(muon)
L(tau)
Photon
(may or may not be a particle)
Particles of light
Photons have no mass, no charge, no baryon number, no lepton number but they do have energy