# Worksheet: Units for Particle Rest Masses

In this worksheet, we will practice using units of eV/c² to express the masses of subatomic particles and converting between eV/c² and kg.

**Q1: **

Particle | Electron | Muon | Tauon |
---|---|---|---|

Mass |

The table shows the masses of the three charged leptons. What is the most massive lepton–antilepton pair that could be produced via pair production from a 150 MeV photon?

- AA tauon–antitauon pair
- BAn electron–positron pair
- CA muon–antimuon pair

**Q2: **

What is kg in keV/? Give your answer to 3 significant figures.

**Q3: **

A muon has a mass of . What is the mass of a muon in kilograms? Give your answer to 3 significant figures.

- A kg
- B kg
- C kg
- D kg
- E kg

**Q4: **

The Feynman diagram shows a sigma baryon decaying into a neutron and a pion.

What particle is represented by in the diagram?

- A
- B
- C
- D
- E

What particle is represented by in the diagram?

- A
- B
- C
- D
- E

**Q5: **

The Feynman diagram shows an antitauon decaying into an antimuon. What particle is represented by in the diagram?

- A
- B
- C
- D
- E

**Q6: **

Is the interaction shown in the Feynman diagram possible? If not, why not?

- AYes
- BNo, because it doesn’t conserve electric charge
- CNo, because it doesn’t conserve strangeness
- DNo, because it doesn’t conserve the baryon number
- ENo, because a W boson cannot decay into a pion

**Q7: **

Which of the following Feynman diagrams shows the interaction ?

- A
- B
- C
- D