The infrared structure of the quark-antiquark scattering kernel in quantumchromodynamics: A clue to the nature of the quark binding potential?

The equal rate, near-mass-shell behavior of the two particle irreducible, spin-independent, color singlet channel quark-antiquark (qq̄) scattering kernel is studied to all orders in perturbation theory. A general functional form in terms of the long-distance Yang-Mills invariant charge g(t),t-->0, t being the momentum transfer, is determined. Under certain conditions, the behavior of the Bethe-Salpeter iteration of this kernel in the qq̄ threshold regime suggests the existence of a universal qq̄ effective potential of the form g²_eff[g(t)]/t.