- #1
llorgos
- 20
- 0
Hi!
I have to prove that the amplitude of the process
[itex]\gamma \gamma \to W^+ W^- [/itex]
does not depend on the gauge we will choose, [itex]R_{\xi}[/itex].
So I use the most general expressions for the propagators and vertices. I find 5 diagrams. One that involves only the 4 fields and a vertex, 1 t and one u channel with a W boson as propagator and 1 t and 1 u where the propagator is a non-physical field [itex]\phi[/itex].
I just sum up the last 4, since the first one does not depend on the [itex]\xi[/itex] parameter but then I am stuck since nothing seems to make the horrible expressions in such a way that there will be no gauge dependence in the end..
Any help?
I have to prove that the amplitude of the process
[itex]\gamma \gamma \to W^+ W^- [/itex]
does not depend on the gauge we will choose, [itex]R_{\xi}[/itex].
So I use the most general expressions for the propagators and vertices. I find 5 diagrams. One that involves only the 4 fields and a vertex, 1 t and one u channel with a W boson as propagator and 1 t and 1 u where the propagator is a non-physical field [itex]\phi[/itex].
I just sum up the last 4, since the first one does not depend on the [itex]\xi[/itex] parameter but then I am stuck since nothing seems to make the horrible expressions in such a way that there will be no gauge dependence in the end..
Any help?