This is the web-site of the working group on theory, MC and tuning of MPI inside the MPI workshop series. We would like to use this forum for sharing of information, development of ideas and maybe even trigger activities to be reported in our next workshop meeting at CERN in (3.-7.12.2012), see https://indico.cern.ch/conferenceDisplay.py?confId=184925 .

We noticed the RecentDevelopments on multi- and double parton pdfs, QCD analysis of double parton scattering, new MC developments on MPI and new tunes.

We think that the following list of questions are important to be addressed: - What is the connection between recent theory developments and MC developments? - Can we think about more exclusive observables with sensitivity to MPI? - We observe that identified particle spectra and their ratios at LHC are not always well described by the models. Does MPI influence the hadronisation? If so, can we quantify the effect with respect to the hadronisation measured at LEP? Can we think of specific observables to answer these questions? - Can we connect pQCD to color reconnection? What is the uncertainty on observables due to color reconnection? - Does MPI need a different tuning for MC setups where the shower and MPI generation is matched to a NLO ME generator?

Conveners of this working group are Judith Katzy, Frank Krauss, Zoltan Nagy, Ted Rogers