Elements of a theory for multiparton interactions in QCD
  We perform a detailed investigation of multiple hard interactions in hadron-hadron collisions. We discuss the space-time, spin and color structure of multiple interactions, classify different contributions according to their power behavior and provide several elements required for establishing all-order factorization. This also allows us to analyze the structure of Sudakov logarithms in double hard scattering. We show how multiparton distributions can be constrained by lattice calculations, by connecting them with generalized parton distributions, and by calculating their behavior at large transverse parton momenta. 
Markus Diehl, Daniel Ostermeier, Andreas Schafer
hep-ph