Principal-Value Resummation for Dilepton Production
  We present a new method of resummation of QCD threshold distributions to the hard scattering function of the dilepton production cross section in hadron-hadron collisions. Our formulation by-passes the infrared singularities of the QCD running coupling through a principal value prescription, and does not require an explicit infrared cut-off. The resulting large corrections exponentiate, and we discuss asymptotic properties of the exponent. We present a closed analytical formula for the resummed hard part in momentum space, and give predictions, at fixed-target energies, for the resulting cross section which is a bounded function of its kinematic variables in the entire partonic phase space. 
H. Contopanagos, L. Alvero and G. Sterman