- All particles of matter are made up of either quarks and/or leptons
- The standard model of particle physics categorises quarks and leptons by charge and mass
Quarks and leptons form the standard model of particle physics. The first generation of particles make up all ordinary matter
- Hadrons are made up of quarks and interact with the strong nuclear force
- Baryons and mesons are types of hadron
- Baryons consist of 3 quarks
- Mesons consist of a quark-antiquark pair
- The most common baryons are protons and neutrons
- The most common mesons are pions and kaons
Hadrons may be either a baryon or a meson. Both baryons and mesons interact with the strong nuclear force
Anti-hadrons may be either an anti-baryon or an anti-meson
- Quarks have never been discovered on their own, always in pairs or groups of three
- Note that all baryons or mesons have integer (whole number) charges eg. +1e, -2e etc.
- This means quarks in a baryon are either all quarks or all anti–quarks. Combination of quarks and anti–quarks don’t exist in a baryon
- The anti–particle of a meson is still a quark and anti–quark pair. The difference being the quark becomes the anti–quark and vice versa
The baryon Δ++ was discovered in a particle accelerator using accelerated positive pions on hydrogen targets.
Which of the following is the quark combination of this particle?
- Remembering quark combinations is useful for the exam
- However, as long as you can remember the charges for each quark, it is easy to figure out the combination by making sure the combination of quarks adds up to the total charge of the particle (just like in the worked example!)