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Flashcards in Particle Classification Deck (43):
1

What are the two groups of particles?

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

2

What are Hadrons?

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

3

What force holds protons together?

Strong nuclear force.

4

What are Hadrons made up of?

Quarks and Anti-Quarks

5

What are the two types of Hadron?

• Baryons( and anti-baryons )
• Mesons

6

What are leptons?

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

7

How do leptons interact?

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

8

How do Hadrons interact?

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

9

How do Hadrons decay?

• Weak Interaction
The proton does not decay because it is stable.

10

What is the energy of particles that collide?

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

11

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

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

12

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

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

13

What are baryons?

• Baryons are protons and other Hadrons that decay into protons

14

What are Mesons?

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

15

What type of particle are protons and neutrons?

Baryons

16

What do all baryons decay into?

Protons.

17

What is the only stable baryon?

Proton

18

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

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

19

Why do you not find antiparticles in normal matter?

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

20

What is the baryon number?

The number of baryons.

21

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

It can only take a certain set of values.

22

What happens to the baryon number in an interaction?

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

23

What happens to neutrons in beta decay?

They change into protons.

24

What interaction is beta decay caused by?

Weak interaction.

25

What happens when a neutron decays?

Forms:
• Proton
• Electron
• Anti-neutrino

26

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

They are not baryons.

27

What is a common feature shared among mesons?

• They are all unstable
• Have a baryon number of 0.

28

How do mesons interact with baryons?

Via the strong force.

29

What are some mesons?

• Kaons
• Pions

30

How do leptons interact with other particles?

Via weak interaction

31

What are the different leptons?

• Muon
• Electron

32

What do Muons decay into?

Ordinary electrons.

33

What are the two types of neutrino for leptons?

• Muon-neutrino
• Electron-neutrino

34

What are neutrinos?

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

35

How do leptons become other leptons?

Through weak interaction.

36

How are leptons produced/annihilated?

Particle-antiparticle interactions

37

What is the lepton number?

• 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.

38

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

• 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.

39

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

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.

40

What is a rule for all lepton interactions?

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

41

What is the lepton number for anti-leptons?

-1

42

What is the lepton number for leptons?

+1

43

What is the lepton number for non leptons?

0