Q98 · Practice questionComplex familiar4 marks
QUESTION 98 (4 marks)
The diagram shows through an intermediate photon. Identify the interaction responsible and show that total lepton number is conserved.
WORKED SOLUTION
4 marksPractice marking scheme
ANSWER
Electromagnetic interaction; total lepton number is 0 before and after.
Worked solution
The intermediate gauge boson is a photon, so this is an electromagnetic interaction. Initially, and , giving total . Finally, and , again giving total . Therefore lepton number is conserved.
Identifies photon as mediator.
Identifies electromagnetic interaction.
Calculates initial lepton number.
Calculates final lepton number and concludes conservation.
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