Jet measurements in ATLAS

The reconstruction of particle jets generated in the proton-proton collisions at the Large Hadron Collider (LHC) at a center of mass energy of sqrt(s) = 7 TeV with the ATLAS detector is discussed. Beginning with a brief review of the calorimeter signal de nitions relevant for jet finding, and the use of reconstructed charge particle tracks, the jet reconstruction strategy is described in some detail. Emphasis is put on the jet energy scale (JES) calibration strategy applied for first data, which is based on a short sequence of data driven and simulation based calibrations and corrections. The level of understanding of the signal patterns entering the JES corrections is shown for selected variables in comparisons to simulations. The present systematic uncertainties on the JES, which can be as low as 2% for central jets, are presented and analyzed with respect to the individual fractional contributions entering their determination. Some characteristic jet reconstruction performance and selected results from the first year of jet physics with ATLAS in a newly accessible kinematic domain are shown in conclusion.