BRAINCAKEBaryons and Mesons
Hadrons are particles made of quarks. Because they contain quarks, they feel the strong force. There are two families:
Baryons are made of three quarks. Each has a baryon number B = +1 (antibaryons, made of three antiquarks, have B = –1). Examples: the proton and the neutron. The proton is the only stable baryon; a free neutron decays with a half-life of about 10 minutes, and other baryons eventually decay into protons.
Mesons are made of a quark and an antiquark. Their baryon number is 1/3 + (–1/3) = 0. Examples: pions (π+, π0, π-) and kaons. All mesons are unstable.
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More in Particle Physics
- Annihilation
- The Standard Model
- Quarks
- Leptons
- Quark Composition of Hadrons
- Conservation Laws in Particle Interactions
- Charge, Baryon Number and Lepton Number
- Particle Interaction Questions
All 19 lessons in Particle Physics · All Edexcel A-level Physics topics