BRAINCAKEBaryons and Mesons
Hadrons are particles made of quarks. They are the only particles that feel the strong nuclear force, and they come in two families: baryons and mesons.
A baryon is made of three quarks. The proton (uud) and the neutron (udd) are baryons. An antibaryon is made of three antiquarks, for example the antiproton (uud). Every baryon has baryon number B = +1 and every antibaryon has B = −1. The proton is the only stable baryon; a free neutron decays with a half-life of about 10 minutes.
A meson is made of one quark and one antiquark, so its baryon number is 0. All mesons are unstable. The OCR specification uses two meson families, pions and kaons:
Sign in free to see the rest of this lesson, the R.E.C.I.P.E. recall steps and the quiz
BrainCake is free. Make an account in seconds and pick up where this page stops.
Key terms in this lesson
- strong nuclear force
- The fundamental force that acts between quarks and holds protons and neutrons together in the nucleus, with a very short range.
- quark
- A fundamental particle that combines with others, bound by the strong nuclear force, to form hadrons such as protons and neutrons.
More in Fundamental Particles
- Hadrons and Leptons
- The Strong Nuclear Force
- Quarks and Antiquarks
- Quark Composition of Protons and Neutrons
- Beta-Minus Decay and Quarks
- Beta-Plus Decay and Quarks
- The Weak Interaction
- Conservation of Charge, Baryon Number and Lepton Number
All 11 lessons in Fundamental Particles · All OCR A-level Physics topics