Q135 · Practice questionComplex familiar5 marks
QUESTION 135 (5 marks)
A neutron is described by valence quarks udd.
a)[2 marks]
Use quark charges to show the neutron has zero electric charge.
b)[1 mark]
State its baryon number.
c)[2 marks]
Name the interaction responsible for changing quark flavour and one gauge boson that mediates it.
WORKED SOLUTION
5 marksPractice marking scheme
ANSWER
Quark flavour change is mediated by the weak interaction, through or (or for neutral-current weak processes, though flavour change here requires ).
Worked solution
Part (a): Charge.
Part (b): The neutron has baryon number because each of its three quarks has baryon number .
Part (c): Quark flavour change is mediated by the weak interaction, through or (or for neutral-current weak processes, though flavour change here requires ).
Part (a): completes the requested reasoning and obtains a correct result.
Part (b): completes the requested reasoning and obtains a correct result.
Part (c): completes the requested reasoning and obtains a correct result.
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