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When can colour charge indices be equated?
I'm currently studying QFT and QCD for the first time and I have a question about the colour charge indices given below. I was asked the following question:
(a) Derive the Feynman rule for the 3-...
- 90
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How to sum over final, and average over initial color states?
Consider the $s$-channel mediated top quark production process
$$ d + \overline d \rightarrow t + \overline t$$
Using the Feynman rules for QCD, the amplitude contains a color factor
$$[c^\dagger _{\...
