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I am trying to compute feynman diagrams with the feynman rules but I encounter some difficulties... Since the gamma matrices, spinnors, etc do not comute, the ordering of the different factor from feynman diagram has an importance. Is there some rules that say where to begin and in which order do we have to compute them?

I know for instance that we have to follow the particle flow but in the case of e+ e- scattering, do I begin with the e+ or the e-, etc ?

Thanks in advance

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# Rules to compute Feynman Diagram with the feynman rules

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