A. Zee, Quantum Field Theory in a Nutshell · Problem IV.6.8

Field Theory Redux

Physics — QFT

Problem

Using the Feynman rules derived in exercise IV.6.7 calculate the amplitude for the physical process

\phi'_1 \to A + A

and show that the dependence on

\xi

cancels out. Compare with the result in exercise IV.6.5. [Hint: There are two diagrams, one with

A

exchange and the other with

\phi_2

exchange.]