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How can we solve IR divergences problem?

  1. Jan 27, 2012 #1
    Please teach me this:
    The UV divergence problems are solved by Renormalization Procedure,but I do not understand how to solve IR divergence problems.
    Thank you very much for your kind helping.
  2. jcsd
  3. Jan 27, 2012 #2


    Staff: Mentor

    I am no expert in re-normalisation but my understanding is it is solved in the same way - by regularisation, imposing a cutoff, and then taking the limit:
    http://www.hep.phys.soton.ac.uk/hepwww/staff/D.Ross/qft/aqft5.pdf [Broken]

    Right now I am going a bit deeper into QFT than I have before and this is something I too am trying to grasp. The following paper really helped me a lot by exposing its mathematical underpinnings:

    Last edited by a moderator: May 5, 2017
  4. Jan 27, 2012 #3


    User Avatar
    Science Advisor

    If you're talking about QED, the usual textbook procedure is to sum the cross section over all possible configurations with soft photons in the final state. See, e.g., Peskin & Schroeder.

    Another approach is to redefine the asymptotic electron states to include soft photon clouds.

    BTW, which textbook(s) are you studying from?
  5. Jan 27, 2012 #4
    I am studying Peskin&Schroeder and I am confused with mass singularities in QCD(Parton evolution).
  6. Jan 28, 2012 #5
    In Peskin&Schroeder (&17.5 Parton Evolution)saying ''.....when quarks and gluons appear in initial state of parton subprocess,...mass singularities do not cancel''.Then I worry if there are any disasters because of the singularities?
  7. Jan 28, 2012 #6
    And are there any differences between the singularities because of p→0 when m=0 and the singularities because of p[itex]^{2}[/itex]→m[itex]^{2}[/itex]?
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