When can we ignore the delta function in th Feynman rules?

  • Thread starter Vereinsamt
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  • #1
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Main Question or Discussion Point

in peskin-schroeder and http://www.hep.phy.cam.ac.uk/batley/particles/handout_04.pdf" [Broken] the amplitude for [tex] e^-e^+\rightarrow \mu^- \mu^+ [/tex] is written using feynman rules as follows
[tex] -iM=[\bar{v}(p_2)(-ie\gamma^\mu )u(p_1)] \frac{-ig_{\mu\nu}}{q^2}[\bar{u}(k_1)(-ie\gamma^\nu )v(k_2)] [/tex]

but what about the delta function integeration? is it already done here?

thanks in advanced!
 
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Answers and Replies

  • #2
I may well be wrong here, but that looks like the M matrix part of the S matrix, and it is the S matrix that has the delta function in it, so you shouldnt be expecting a delta function.

again i DID only just do this, so i may be wrong.
 

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