Solution
= Solution
\b[Allowed.] There are again two <tree-level Feynman diagrams>: $t$-channel <Z boson> exchange and the crossed charged-current diagram with a <W boson> exchanged between the neutrino and electron lines.
The complete tree-level list for (ii), (iv), and (v) is:
\Image[/media/past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2019/iii/paper-305-standard-model-processes.png]
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