The static PQCD potential with modified boundary conditions
  We calculate the potential between two static quarks in QCD using modified boundary conditions for the perturbative expansion. Through a change of the Feynman iepsilon prescription we effectively add a "sea" of gluons to the asymptotic states with energies below a given scale Lambda. We find that the standard result for the static potential gets corrections of order Lambda^2/Q^2 both at small and large momentum transfers Q^2. After resummation of the infrared sensitive corrections we find that the running coupling alpha_s(Q^2) freezes in the infrared and that the exchanged gluon gets an effective tachyonic mass. We verify that identical results are obtained in the Coulomb and Feynman gauges. 
Paul Hoyer (Nordita) and Johan Rathsman (CERN)