Studies of vector boson+jet production with ATLAS

The production of vector bosons in association with jets has been studied in proton-proton collisions at √ s = 7 TeV with the ATLAS detector at the LHC. Cross sections have been determined differentially in several kinematic variables and up to high jet multiplicities. For the exclusive 1 jet case also the ratio of the W+1 jet to the Z+1 jet cross section has been measured. The results are compared to the latest fixed-order predictions at NLO and to predictions of generators that use LO or NLO matrix elements supplemented by parton showers. Good agreement is observed between data and most predictions. However, for inclusive quantities such as the scalar pT sum HT , the results demonstrate the need to include higher multiplicity matrix elements in fixed-order NLO calculations.