Compton scattering with off-shell photon

AI Thread Summary
The discussion centers on calculating the modulus of squared amplitude for the process e-γ*→e-γ, involving a virtual photon. The inquiry specifically addresses how to treat a virtual photon in an external leg within Feynman diagrams. It is emphasized that this scenario typically represents a sub-diagram in a broader Feynman diagram, relevant in vacuum quantum field theory (QFT). The need for context regarding the specific physics for which the off-shell amplitude is being calculated is highlighted as essential for providing a comprehensive answer. Understanding the role of external legs in representing asymptotic free states is crucial for progressing in this calculation.
Marioweee
Messages
18
Reaction score
5
Homework Statement
Compute the squared modulus of the summed amplitude over the final and initial polarizations of Compton process with a virtual photon.
Relevant Equations
.
How is it treated or what Feymann's rule applies to a virtual photon in an external leg? I would like to calculate the modulus of squared amplitude for the process

e-γ*→e-γ

where the * indicates that the photon is virtual. I've never dealt with virtual particles on a external leg and would like to know how to get started.
Thank you.
 
Physics news on Phys.org
I've no idea, what the goal is. This can only be a sub-diagram in a true Feynman diagram, which in "vacuum QFT" always describes S-matrix elements with external legs symbolizing asymptotic free states. So to answer this question, we'd need the context, for which physics such an "off-shell amplitude" should be calculated.
 
Thread 'Help with Time-Independent Perturbation Theory "Good" States Proof'
(Disclaimer: this is not a HW question. I am self-studying, and this felt like the type of question I've seen in this forum. If there is somewhere better for me to share this doubt, please let me know and I'll transfer it right away.) I am currently reviewing Chapter 7 of Introduction to QM by Griffiths. I have been stuck for an hour or so trying to understand the last paragraph of this proof (pls check the attached file). It claims that we can express Ψ_{γ}(0) as a linear combination of...
Back
Top