Multiple Parton Interactions, Underlying Event and Forward Physics at LHC

A variety of physics measurements in the low and high P_T regimes will be performed by the LHC experiments in proton-proton collisions at sqrt(S) =14 TeV to study the Multiple Parton Interactions (MPI) processes . The amount of activity in Minimum Bias and high P_T events will be quantified studying charged tracks and calorimetric clusters. The contribution of $MPI$ to the Underlying Event (UE) will be studied by examining the production of charged particles in the region transverse to jets and in the central region of Drell-Yan muon pairs production. The effective double parton scattering cross section is expected to be measured in different topologies. The study of the activity in diffractive topologies will allow disentangling the MPI component of the Underlying Event from the Beam Remnant and Radiative components.