High-pT Jet Distributions and Properties of Inelastic pp Collisions at √s = 7TeV

Making use of the excellent calorimetry of the ATLAS experiment, measurements of the cross-section for jet production and of jet properties in proton-proton interactions at sqrt(s) = 7 TeV will be presented. The corrected and unfolded inclusive cross-section for high-pT jets will be described, together with the cross-section as a function of the invariant di-jet mass. Furthermore, the corrected distribution of the angular difference between the two leading jets will be shown, both for the azimuthal as well as for the polar angle. Also studies of the shape of the observed jets will be presented. All results will be compared to theoretical predictions. The dijet angular distributions in bins of dijet invariant mass are analyzed with the first $7$~TeV $pp$ collisions recorded with the ATLAS detector. The data are confronted with Standard Model predictions with the goal of searching for new phenomena characterized by a contact interactions approach. Finally measurements of the properties of proton-proton interactions at center-of-mass energies ranging from 900 GeV (injection energy) to 7 TeV in the ATLAS detector are presented for a well defined kinematic region. Using charged particles (unfolded and corrected from observed tracks for detector effects), spectra in transverse momentum, pseudo-rapidity and particle density are studied in an inclusive manner. In addition, the momentum flow with respect to a high pT reference track is investigated to study the transition to the underlying event in high pT collisions. Using charged particles allows also to study the kinematic properties of jets built from tracks. The results are compared to Monte Carlo models and have been used to derive Monte Carlo tunes using the first ATLAS measurements from LHC to constrain model parameters.