Measurement of hard double-partonic interactions in W $\to$ l$\nu$ + 2 jet events using the ATLAS detector at the LHC

The third international workshop on multiple partonic interactions (MPI) took place at DESY in Hamburg from 21 to 25 November 2011. MPI are often crucial for interpreting results obtained at the Large Hadron Collider (LHC). The quest for a sound understanding of the dynamics behind MPI { particularly in the era of the LHC { has thus focused the aim of this workshop. It concentrated on phenomenology at previous hadron colliders and early LHC results, as well as theoretical considerations and the modeling of MPI in Monte Carlo event generators. The workshop forstered close contact between the experimental and theoretical communities. It provided a setting to discuss many of the dierent aspects of MPI, eventually identifying them as a unifying concept between apparently dierent lines of research and evaluating their impact on the LHC physics programme. In a total of 45 plenary talks, two round table discussions and a poster session, the workshop covered experimental results, Monte Carlo development and tuning, phenomenology and dedicated measurements of MPI, progress of theoretical understanding as well as the role of MPI in diraction and small-x physics. Connections to closely related research within the elds of heavy ion physics and cosmic rays have also been covered