QCD Studies at LHC with the ATLAS detector

The strong interaction will govern the production of most objects in proton-proton collisions at LHC. A thorough understanding of the strong interaction in this new kinematic regime will be mandatory. This will firstly concern the properties of inelastic interactions, which will be studied by ATLAS by example via measurements of the central charged particle density and transverse momentum spectra. Even with early data, these measurements will be able to distinguish between different models, since current extrapolations from existing data to the LHC energy range suffer from large uncertainties. A proper understanding of these events will also be important for phases of higher luminosity at LHC (and the search for new physics beyond the Standard Model), where several inelastic interactions can occur in a single bunch crossing. A further test of QCD predictions to be performed by ATLAS is the associated production of W (or Z) bosons with one or more jets. Furthermore, details of modern jet algorithms have been studied by ATLAS in detail, in view of their application in jet cross section measurements and other physics analyses. This contribution will present the expected performance on the above mentioned processes and further studies.