Measurements of V +jet production and MPI with ATLAS

The production of jets in association with a W or Z boson in proton-proton collisions at 7 TeV study multileg QCD diagrams. The cross section, differential in several kinematics variables, has been measured up to high jet multiplicities and compared to new higher-order QCD calculations. The ratio of (Z + a single jet)/(W + a single jet) can provide a very precise test of QCD and has also been measured. Topologies with with a vector boson and jets in the final state are also sensitive to double parton scattering which has been measured using W+2 jet events. The contribution of double parton scattering is also sizable for W+b production which has been measured with the ATLAS detector and compared to QCD calculations.