Analysis of inter-quark interactions in classical chromodynamics
  The QCD gluon equation of motion is solved approximately by means of the Green function. This solution is used to reformulate the Lagrangian of QCD such that the gluon propagator appears directly in the interaction terms of the Lagrangian. The nature of the interactions is discussed. Their coordinate-space form is presented and analyzed in the static, non-relativistic case. 
Jurij W. Darewych and Askold Duviryak
hep-th