Multiple parton interactions in Z+4j, W±W±+0/2j and W+W-+2j production at the LHC

The expected rate for Multiple Parton Interactions (MPI) at the LHC is large. This requires an estimate of their impact on all measurement foreseen at the LHC. Conversely it provides new means of studying MPI at the LHC. In this paper we examine the role of MPI at the LHC, with the design energy of 14TeV, in Z production in association with four jets, (WW +/-)-W-+/- in association with zero or two jets, W+W- in association with two jets. In all cases the vector bosons are assumed to decay leptonically. The MPI contribution to Z + 4j is dominated by events with two jets with balancing transverse momentum. It is possible to achieve a good signal to background ratio, close to 20%, for MPI compared to Single Interaction processes by selecting events with two jets with large separation in the transverse plane. The corresponding statistical significance for a luminosity of 1 fb(-1) is about 6.9 for the mu(+) mu(-) channel alone. The final state channel in which only two same-sign high transverse momentum charged leptons are required and additional hard jets are vetoed is dominated by MPI, with an expected yield of 2500 events with the full LHC luminosity.