Jet energy scale calibration using photon-jet events in the ATLAS experiment

A precise calibration of the jet energy in the ATLAS experiment at LHC is fundamental for many physics issues. Di-jet and multi jet events will be used to cross-check the relative response across different pseudo-rapidity and transverse momentum regions. The photon + jet channel (being the one with largest cross section) is the first candidate to check in situ the jet absolute energy scale. In events with photon and a recoiling jet, the transverse momentum balance can be exploited to estimate the jet energy using the measurement on the photon, whose scale is much better under control. The main background to this channel is given by QCD events where one jet is misidentified as a photon. The status of this analysis with the data collected by ATLAS in 2010 will be presented.