Jet and Missing Transverse Momentum Reconstruction, Calibration and Performance with the ATLAS Detector at LHC

Jet and Missing Transverse Momentum (EtMiss) performances in the ATLAS detector are highly deteriorated due to the high instantaneous luminosity achieved in 2012 at the LHC leading to unprecedented backgrounds from additional proton-proton collisions (pile-up interactions) superimposed to the hard physics process. Several approaches to suppress pile-up coherently in jets and in EtMiss soft event contribution are described in this paper. These techniques based on calorimeter signals and reconstructed tracks are a key part of the multi-step approach adopted by ATLAS to reconstruct and calibrate jets and EtMiss. In particular a high precision is obtained for the jet energy scale (JES) in 2012 with in-situ techniques leading to a resulting uncertainty smaller than 2.5% for jet with pT > 100 GeV in the central calorimeter region.