Particles and radiation chapter 2: Quarks and leptons

Question 1

What are the two main particle classifications?

Answer 1

Hadrons and leptons.

Question 2

What is the difference between hadrons and leptons?

Answer 2

Leptons are fundamental particles, and do not experience the strong nuclear force.

Hadrons are made up of quarks (fundamental particles), and experience the strong nuclear force.

Question 3

Name the different classification of hadrons And give their components.

Answer 3

• Baryons (made of three quarks)
• Antibaryons (made of three antiquarks)
• mesons (1 quark and 1 antiquark)

Question 4

Why is the proton significant?

Answer 4

The proton is the only stable baryon, therefore all baryons will decay into a proton eventually.

Question 5

Name all fundamental particles.

Answer 5

• electron / positron
• muon / antimuon
• electron neutrino / electron antineutrino
• muon neutrino / muon antineutrino

Question 6

Define the term “Baryon number”

Answer 6

• The baryon number of a particle shows whether it is a baryon (if 1), antibaryon (if -1), or not a baryon (if 0).
• Baryon number is always conserved in particle interactions.

Question 7

What is a muon?

Answer 7

A muon (sometimes known as a heavy electron) is a lepton that decays into an electron.

Question 8

Define the term “lepton number”

Answer 8

The lepton number of a particle shows whether it is a lepton (if 1), anti lepton (if -1) or not a lepton (if 0). There are two types: electron lepton number and muon lepton number. lepton number is always conserved in particle interactions.

Question 9

Define the term “strange particles”

Answer 9

Strange particles are particles that are produced by the strong nuclear interaction but decay by the weak interaction.

Question 10

What are kaons?

Answer 10

Kaons (either K+,K- or K0) are strange particles which decay into pions through the weak interaction.

Question 11

name the three types of quarks and their antiquarks.

Answer 11

• Up (u) / anti up (/u)
• Down (d) / Anti down (/d)
• Strange (s) / anti strange (/s)

Question 12

Write the equation for the decay of a neutron into a proton.

Answer 12

Question 13

Which properties must always be conserved in particle interactions?

Answer 13

• Energy
• Momentum
• Charge
• Baryon number
• Electron lepton number
• Muon lepton number
• Strangeness (if the interaction is strong)

Question 14

What is a pion?

Answer 14

The pion is a particle that has a rest mass greater than a muon but less than a proton. (∏⁰, ∏^-, or ∏⁺)