Double parton scattering in the ultraviolet: addressing the double   counting problem
  In proton-proton collisions there is a smooth transition between the regime of double parton scattering, initiated by two pairs of partons at a large relative distance, and the regime where a single parton splits into a parton pair in one or both protons. We present a scheme for computing both contributions in a consistent and practicable way. 
Markus Diehl, Jonathan R. Gaunt
hep-ph