Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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


    User Avatar
    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)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook