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

Coulomb Singularity

  1. Apr 27, 2010 #1
    Hi all,
    I am just new to work on NLO in QCD. I need to know how a Coulomb singularity in QCD is defined? What is the form/expression of this singularity term? Can anyone explain with an example of any Feynman diagram? I am interested in the case of a quarkonium with two gluons in final state. I'll be really grateful for the help.
     
  2. jcsd
  3. Apr 27, 2010 #2

    tom.stoer

    User Avatar
    Science Advisor

    Can you explain what you mean by Coulomb singularity in QED?
     
  4. Apr 28, 2010 #3
    Coulomb singularity appears whenever a virtual gluon is exchanged between quark pair of a meson. The limit that relative velocity of these two quarks tends to zero (to make a bound state for meson) in an expression ~ 1/v (v being realative velocity here) generates this singularity. This is what I know so far. I'm not sure where does this expression ~1/v come from? :cry: And with this information, I think we have Coulomb singularities only in QCD, but not in QED. :confused:
    Can anybody please help or refer me to some good derivation of this??? PLZZZZZZZZ
     
  5. Apr 28, 2010 #4

    tom.stoer

    User Avatar
    Science Advisor

    I do not know about which model you are talking. QCD, low-energy effective XYZ, non-relativistic quark model, .... I have never seen 1/v in full QCD.
     
  6. Apr 28, 2010 #5
    Ooops, I really forgot to mention this. I'm talking about NRQCD.
     
  7. Apr 28, 2010 #6

    tom.stoer

    User Avatar
    Science Advisor

    any references? on arxiv?
     
  8. Apr 28, 2010 #7
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook