In-situ jet energy calibration methods in ATLAS at the CERN LHC

The physics goal of the ATLAS collaboration involving searches for new particles and precise measurements sets the chalenging goal to know the jet energy scale to an accuracy of 1%. In-situ calibration methods are reviewed. Calibration using energetic isolated charged hadrons will be a powerful tool to transfer the calibration from the test beam to the detector and would guarantee an inter-calibration between modules and calorimeters. The next step is the understanding of the absolute jet energy scale. The W mass reconstruction method, based on the well-known W mass and the very large statistics of W -> jj decays from top quark decay, and the pT-balance method, based on events containing a Z boson decaying to leptons balanced by one high-pT jet, should provide adequate tools to achieve the required overall 1% uncertainty.