Measurements of QCD in W/Z and multijet events in ATLAS

Precision measurements of the production cross sections of diphoton and dijet events, as well as the production cross section and W/Z bosons in association with jets, provide important tests of perturbative QCD. In this talk, recent measurements of such processes from the ATLAS collaboration are presented. They include measurements of the prompt inclusive photon production, the measurement of ratios of jet-production rates and the measurement of several event-shape jet observables. The measurements of jet observables are used to determine the strong coupling constant. Moreover, differential Z+jets results in extreme phase-spaces with high pT jets are discussed, followed by the measurement of the production of a W boson in association with D+ and D*+ mesons that provides information about the strange content of the proton. The measurements are compared to state-of-the-art NLO and NNLO predictions. Finally, measurements of the transverse momentum distribution of W and Z bosons are highlighted and compared to theoretical calculations based on parton shower Monte Carlo generators and analytic resummation approaches. The strong coupling constant is determined with highest precision.