Particle Classification

Question 1

What are the two groups of particles?

Answer 1

• Hadrons
• Leptons
Grouped based upon whether or not they interact through strong interaction

Question 2

What are Hadrons?

Answer 2

Particles and antiparticles that interact through the strong interaction ( particles that feel strong nuclear force ).

Question 3

What force holds protons together?

Answer 3

Strong nuclear force.

Question 4

What are Hadrons made up of?

Answer 4

Quarks and Anti-Quarks

Question 5

What are the two types of Hadron?

Answer 5

• Baryons( and anti-baryons )

* Mesons

Question 6

What are leptons?

Answer 6

• Fundamental Particles and antiparticles that do not interact through strong interaction ( they do not feel strong nuclear force ).

Question 7

How do leptons interact?

Answer 7

• Weak interaction
• Gravitational Interaction
• Electromagnetic Interaction, if they are charged.

Question 8

How do Hadrons interact?

Answer 8

All four fundamental interactions.
• Strong Interaction
• Electromagnetic interaction if charged.

Question 9

How do Hadrons decay?

Answer 9

• Weak Interaction

The proton does not decay because it is stable.

Question 10

What is the energy of particles that collide?

Answer 10

Total energy of the particles & antiparticles before collision = rest energy + kinetic energy

Question 11

What is the formula for the energy of new particles after collision?

Answer 11

New particles and antiparticle energy after the collision = rest energy + kinetic energy

Question 12

how do baryons and mesons differ in terms of their decay?

Answer 12

• Baryons are protons and other Hadrons that decay into protons
• Mesons are Hadrons that do not include protons in their decay products.

Question 13

What are baryons?

Answer 13

• Baryons are protons and other Hadrons that decay into protons

Question 14

What are Mesons?

Answer 14

• Mesons are Hadrons that do not include protons in their decay products.

Question 15

What type of particle are protons and neutrons?

Answer 15

Baryons

Question 16

What do all baryons decay into?

Answer 16

Protons.

Question 17

What is the only stable baryon?

Answer 17

Proton

Question 18

What type of particles are the antiparticles of protons and neutrons?

Answer 18

Anti-protons and anti-neutrons are the antiparticles of protons and neutrons.
These particles are anti-baryons.

Question 19

Why do you not find antiparticles in normal matter?

Answer 19

Antiparticles are annihilated when they meet their corresponding particles, thus you cannot find them in normal matter.

Question 20

What is the baryon number?

Answer 20

The number of baryons.

Question 21

What does it mean for the baryon number to be a quantum number?

Answer 21

It can only take a certain set of values.

Question 22

What happens to the baryon number in an interaction?

Answer 22

It is conserved, the total baryon number in any particle interaction never changes

Question 23

What happens to neutrons in beta decay?

Answer 23

They change into protons.

Question 24

What interaction is beta decay caused by?

Answer 24

Weak interaction.

Question 25

What happens when a neutron decays?

Answer 25

Forms: • Proton • Electron • Anti-neutrino

Question 26

Why do electrons and anti-neutrinos have a baryon number of zero?

Answer 26

They are not baryons.

Question 27

What is a common feature shared among mesons?

Answer 27

* They are all unstable | * Have a baryon number of 0.

Question 28

How do mesons interact with baryons?

Answer 28

Via the strong force.

Question 29

What are some mesons?

Answer 29

* Kaons | * Pions

Question 30

How do leptons interact with other particles?

Answer 30

Via weak interaction

Question 31

What are the different leptons?

Answer 31

* Muon | * Electron

Question 32

What do Muons decay into?

Answer 32

Ordinary electrons.

Question 33

What are the two types of neutrino for leptons?

Answer 33

* Muon-neutrino | * Electron-neutrino

Question 34

What are neutrinos?

Answer 34

Particles with zero or almost zero mass, and zero electric charge.

Question 35

How do leptons become other leptons?

Answer 35

Through weak interaction.

Question 36

How are leptons produced/annihilated?

Answer 36

Particle-antiparticle interactions

Question 37

What is the lepton number?

Answer 37

* Number of leptons, each lepton has a number of +1. * There are two types of lepton numbers, electron and muon. * These different lepton numbers must be counted separately.

Question 38

What happens in an interaction between a lepton and a Hadron?

Answer 38

* A neutrino or anti-neutrino can change into or from a corresponding charged lepton. * An electron neutrino can therefore interact with a neutron to produce a proton and an electron. * An electron neutrino and a neutron can not change into an anti-proton and a positron.

Question 39

Why can an electron neutrino and a neutron not change into an anti-proton and a positron?

Answer 39

The lepton number is not conserved: Ve + n > (anti)P + e+ Lepton number of +1 in the left, Lepton number of -1 on the right, no conservation.

Question 40

What is a rule for all lepton interactions?

Answer 40

Both types of lepton number must be conserved in any change.

Question 41

What is the lepton number for anti-leptons?

Answer 41

-1

Question 42

What is the lepton number for leptons?

Answer 42

+1

Question 43

What is the lepton number for non leptons?

Answer 43

0