Griffiths Introduction to Elementary Particles · Problem 2.8

Relativistic Kinematics — David J. Griffiths

Physics — QFT · feynman-diagrams-mixed-interactions

Problem

Some decays involve two (or even all three) different forces. Draw possible Feynman diagrams for the following processes: ((a))

K^+ \rightarrow \mu^+ + \nu_\mu + \gamma

((b))

\Sigma^+ \rightarrow p + \gamma

What interactions are involved? (Both these decays have been observed, by the way.)