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S-Matrix in non-relativistic limit

  1. Feb 23, 2010 #1
    I have a problem in deriving the formula :
    [tex]\left \langle p^\prime | iT | p \right\rangle = -2\pi i\widetilde{ V}(q)\delta(E_{p^\prime}-E_{p})[/tex]
    which is in Peskin's QFT book. How to derive it?
    Is there anything to do with [tex] \psi = e^{i\vec{k}\cdot\vec{r}}+\frac{f(\theta)}{r}e^{i\vec{k^\prime}\cdot\vec{r}}[/tex] ?
     
  2. jcsd
  3. Feb 24, 2010 #2

    Meir Achuz

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    The energy delta function comes from an integral of the exponential time factors in
    \psi(r,t)~exp[i(E_p-E-p')].
    The V(q) is the Fourier transform of the potential.
     
  4. Feb 26, 2010 #3
    Thank you :)
     
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