Close-by Jet Effects on Jet Energy Scale Calibration in pp Collisions at sqrt(s)=7 TeV with the ATLAS Detector

The jet energy scale (JES) and systematic uncertainty determined by ATLAS using the full 2010 data-set of 7 TeV proton-proton collisions are applicable to isolated jets that have no other jet within a certain distance in the rapidity and azimuthal angle space. Presence of any jets near-by could cause difference in jet response, and hence result in an additional JES systematic uncertainty. Relative response of jets reconstructed using calorimeter and inner detector information and the comparison between data and Monte Carlo simulations are exploited to assess the additional contribution given to the JES uncertainty due to the presence of a close-by jet using the present integrated luminosity of 38 pb-1. The close-by jet systematic uncertainty is evaluated to be less than 3% for jets with transverse momentum larger than 20~GeV and absolute rapidity less than 2.0.