# Homework Help: Scalar electron-muon scattering

1. Dec 11, 2017

### Milsomonk

1. The problem statement, all variables and given/known data
Consider the scattering of a scalar electron and a spin half muon, draw and label the feynman diagram for this process.
write down the invariant amplitude M and the spin average |M|^2, use the trace notation.

2. Relevant equations
Photon propagator
$$\dfrac {-i\eta_{\mu\nu}}{k^2}$$

3. The attempt at a solution
Ok so I have written down what I think the correct labelled feynman diagram is, apologies that its attached as a photo, I did draw it in latex but it doesn't want to compile on here. It's possible I havn't gone about this the correct way, I can't find any examples of scalar particles scattering with spin half particles so I just tried it the only way I could think of. I'm not sure how to write the spin average matrix in terms of traces, I know it should have something to do with the fact that are multiple spin states for the initial and final states of the muon (two) but I don't know how to rwite this down mathematically. Any guidance would be greatly appreciated :)

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2. Dec 16, 2017

### PF_Help_Bot

Thanks for the thread! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post? The more details the better.