Proceedings of the Workshop MPI@LHC 2015

The workshopMPI@LHC 2015was held in a very nice and inspiring atmosphere of the Abdus SalamInstitute for Theoretical Physics in Trieste from 23 - 27 November 2015 at Miramare, Trieste, Italy. Thisworkshop was the 7th workshop in a series of workshops on Multiparton Interactions (MPI) which startedalready in 2006 at DESY [1] and then continues as the MPI@LHC workshops with a kickoff meeting in2008 in Perugia [2], Italy, and continued with workshops in Glasgow [3] in 2010, DESY [4] in 2011, CERN[6] and Tel Aviv [5] in 2012, in Antwerp [7] in 2013 and in Cracow [8] in 2014. From the start of the experimental activity of the Large Hadron Collider, Multiple Partonic Interactions(MPI) are experiencing a growing popularity and are widely invoked to account for observations that cannotbe explained otherwise. This includes associated hadron production (Underlying Event) in high energyhadronic collisions with jets, the rates for multiple heavy flavor production, the survival probability of largerapidity gaps in hard diffraction, etc. In particular in recent years Double Parton Interactions were observeddirectly and studied by a number of the FNAL and LHC experiments in different reaction channels. At the LHC a new QCD regime has now been reached, where MPIs occur with high rates, in particular incentral collisions, which give dominant contribution to production of new particles Understanding MPIs istherefore crucial, both for their significant contribution to the background of various processes of interestfor the search of new physics and because MPIs are an interesting topic of research by itself, allowing toprobe high energy - high density QCD dynamics and, as a consequence of the geometrical characteristicsof the interaction, to obtain unprecedented information on the correlated structure of the QCD bound states. The aim of this workshop is to provide an updated view of MPI studies, both experimental and theoretical, and to foster contacts between theoretical and experimental communities active in the field. The workshop held in Trieste in 2015 was a special workshop in the sense that many investigations andanalyses from LHC run1 were still finalized, presented and compared to model calculations and at the sametime the very new first measurements from run2 at the highest center of mass energy of pp collisions of√s= 13TeV were presented.