Jet energy measurement and its systematic uncertainty in proton--proton collisions at √s=7TeV with the ATLAS detector

The jet energy scale (JES) and its systematic uncertainty are determined for jets measured with the ATLAS detector using proton--proton collision data with a centre-of-mass energy of (Formula presented.)(Formula presented.)TeV corresponding to an integrated luminosity of (Formula presented.)(Formula presented.)(Formula presented.)(Formula presented.). Jets are reconstructed from energy deposits forming topological clusters of alorimeter cells using the anti-(Formula presented.)(Formula presented.) algorithm with distance parameters (Formula presented.)(Formula presented.) or (Formula presented.)(Formula presented.), and are calibrated using MC simulations. A residual JES correction is applied to account for differences between data and MC simulations. This correction and its systematic uncertainty are estimated using a combination of in situ techniques exploiting the transverse momentum balance between a jet and a reference object such as a photon or a (Formula presented.)(Formula presented.) boson, for (Formula presented.)(Formula presented.) and pseudorapidities (Formula presented.)(Formula presented.). The effect of multiple proton--proton interactions is corrected for, and an uncertainty is evaluated using in situ techniques. The smallest JES uncertainty of less than 1 \% is found in the central calorimeter region ((Formula presented.)(Formula presented.)) for jets with (Formula presented.)(Formula presented.). For central jets at lower (Formula presented.)(Formula presented.), the uncertainty is about 3 \%. A consistent JES estimate is found using measurements of the calorimeter response of single hadrons in proton--proton collisions and test-beam data, which also provide the estimate for (Formula presented.)(Formula presented.) TeV. The calibration of forward jets is derived from dijet (Formula presented.)(Formula presented.) balance measurements. The resulting uncertainty reaches its largest value of 6 \% for low-(Formula presented.)(Formula presented.) jets at (Formula presented.)(Formula presented.). Additional JES uncertainties due to specific event topologies, such as close-by jets or selections of event samples with an enhanced content of jets originating from light quarks or gluons, are also discussed. The magnitude of these uncertainties depends on the event sample used in a given physics analysis, but typically amounts to 0.5--3 \%. \copyright 2014, CERN for the benefit of the ATLAS collaboration.