- #1
taishizhiqiu
- 63
- 4
In 'an introduction to quantum field theory' by peskin, he writes: To analyze the photon one-point function, note that the external photon must be attached to a QED vertex. Neglecting the external photon propagator, this amplitude is therefore:
I really cannot justify this equation. Can anyone explain it to me?
I really cannot justify this equation. Can anyone explain it to me?