Recent QCD results from ATLAS

The ATLAS collaboration has performed studies of a wide range of QCD phenomena. Recent soft-QCD measurements include studies of underlying event, hadronic event shapes, double parton scattering, diffraction, internal jet structure, jet shapes for heavy quark jets and forward energy flow. Differential measurements of inclusive and dijet production provide stringent tests of higher order QCD predictions and provide input for determination of parton density functions. Inclusive jet multiplicity ratios are sensitive to the strong coupling constant alpha_S. Measurements of the inclusive prompt isolated photon and diphoton cross sections provide a direct probe of short-distance physics. The results are compared to various theoretical models and next-to-leading-order or higher-order QCD calculations.