Quarks and Leptons (AS) Flashcards
Define a muon
A muon (or a heavy electron), is a negatively charged particle with a rest mass over 200 times the rest mass of an electron
Define a pion
A particle which can be positively charged (π+), negatively charged (π-) or neutral (π^0), and has a rest mass greater than a muon but less than a proton.
Define a kaon
A particle which can be positively charged, or negatively charged or neutral. It has a rest mass greater than a pion but still less than a proton.
What are quarks?
They are fundamental particles that make up particles such as protons and neutrons. They exert the strong nuclear force on one another.
What are the 6 ‘flavours’ of quarks?
- Up
- Down
- Strange
- Charm
- Bottom
- Top
What are gluons? (3)
- They are 1 of the 4 exchange particles of the standard model.
- Gluons act between quarks holding them together.
- Gluons have an extremely short range of action, about 10^-15 m
What is deep-inelastic scattering? (3)
- Involves firing electrons at protons at very high energies
- It’s ‘inelastic’ because the kinetic energy from the collision is converted into other forms (electrons penetrate into protons, and interact with the quarks via exchange of photons).
- KE is converted into mass as the photon shatters producing a shower of the particles.
What are the 4 fundamental forces?
- Electromagnetic force
- Strong nuclear force
- Weak force
- Gravity
What are the 3 main groups of particles?
- Hadrons
- Leptons
- Exchange particles
What are the exchange particles of the 4 fundamental forces?
- Electromagnetic - Photon
- Strong nuclear - Gluon
- Weak - W± / Z
- Gravity - Graviton
What are hadrons? And what can they be further grouped into?
- Made up of quarks, and they ‘feel’ the strong force.
2. Mesons and Baryons
Explain fully, what Mesons are. With examples
- A quark-antiquark pair
2. Examples: Pion (π+), Kaon (K+); plus anti-particles.
Explain fully, what Baryons are. With examples
- 3 quarks e.g. qqq (or anti baryons)
- Examples:
- Protons (uud)
- Neutron (udd)
- plus antiparticles
What are Leptons?
- Fundamental particles
2. Made up of electrons, muons and tau particles, their neutrinos and antiparticles.
What force do leptons interact with?
Leptons interact through the weak interaction, gravitational interaction, and electromagnetic interaction (if charged). Leptons don’t ‘feel’ the strong force.
