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Why we do not consider the divergence due to mass-shell in QED?

  1. Jan 30, 2012 #1
    Please teach me this:
    Why we do not consider the divergences in loops in QED when p[itex]^{2}[/itex]→m[itex]^{2}[/itex] but only consider the soft photon when k[itex]^{2}[/itex]→0(IR divergence) and UV divergence?
    Thank you very much in advance.
     
  2. jcsd
  3. Jan 30, 2012 #2

    tom.stoer

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    Science Advisor

    p²-m² is always regulated via the "iε-Term" and is evaluated via the Cauchy contour integral
     
  4. Jan 30, 2012 #3
    Why we have not the same consideration when m=0?
     
  5. Jan 30, 2012 #4
    Sorry,Now I have understood.Applying Cauchy's theorem when m=0(so k[itex]^{2}[/itex]→0)
    we have divergence(IR divergence)
     
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