# 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 Mass Electron Muon Tauon 511/𝑐keV 106/𝑐MeV 1.78/𝑐GeV

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
• BA muon–antimuon pair
• CAn electron–positron pair

Q2:

What is kg in ? 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? • ANo, because a W boson cannot decay into a pion
• BNo, because it doesn’t conserve strangeness
• CNo, because it doesn’t conserve the baryon number
• DNo, because it doesn’t conserve electric charge
• EYes

Q7:

Which of the following Feynman diagrams shows the interaction ?

• A • B • C • D Q8:

Which of the following equations represents the Feynman diagram shown? • A
• B
• C
• D
• E

Q9:

Which of the following equations represents the Feynman diagram shown? • A
• B
• C
• D
• E

Q10:

The Feynman diagram shows a lambda baryon decaying into a proton and a pion. What particle is represented by X in the diagram? • A
• B
• C
• D
• E

Q11:

The Feynman diagram shows a down quark decaying into an up quark, producing a boson, which decays into an electron and an electron antineutrino. Which of the particles shown in the diagram is a virtual particle? • A
• B
• C
• D
• E