- #1
Milsomonk
- 96
- 17
Hi guys,
And Happy new year :) I am revising for a module on relativistic quantum mechanics currently that I took some time ago.
A large portion of the module, and hence the exam involves drawing Feynman diagrams and computing invariant amplitudes. The part I am a little rusty on is how to know how many diagrams there are for a particular process, and when I must add the two together in order to obtain the invariant amplitude.
Any general advice would be appreciated but I realize this could be a little vague so here is a more concrete example from a past paper.
Consider a spin-1/2 particle ψ of charge q and mass m, and a spin-0 particle φ of the same mass and charge. Draw the lowest order Feynman diagram for the process
ψφ → ψφ
What I am not sure of is whether there is one or two diagrams here that contribute to the invariant amplitude?
Many thanks
And Happy new year :) I am revising for a module on relativistic quantum mechanics currently that I took some time ago.
A large portion of the module, and hence the exam involves drawing Feynman diagrams and computing invariant amplitudes. The part I am a little rusty on is how to know how many diagrams there are for a particular process, and when I must add the two together in order to obtain the invariant amplitude.
Any general advice would be appreciated but I realize this could be a little vague so here is a more concrete example from a past paper.
Consider a spin-1/2 particle ψ of charge q and mass m, and a spin-0 particle φ of the same mass and charge. Draw the lowest order Feynman diagram for the process
ψφ → ψφ
What I am not sure of is whether there is one or two diagrams here that contribute to the invariant amplitude?
Many thanks