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...
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...