  Multiple parton interactions in a single proton-proton collision are expected
to play an important role for many observables at LHC. To a large part their
phenomenological description relies on rather simple and physically intuitive
assumptions. We report on an investigation of multiple hard interactions in
QCD, which aims at identifying to which extent this simple description arises
from theory and where it needs to be extended. An approximate connection with
generalized parton distributions may help elucidate some aspects of
multiple-interaction dynamics.
