Insitu Jet Energy Scale Calibration using the ATLAS Detector

When a highly energetic gluon or quark flies out of an LHC collision, it will produce a collimated shower of high energy hadrons called a jet. Such objects are extremely prevalent in searches involving the decay of heavy particles such as Higgs, top, and more exotic particles. Therefore, it is critical to model the detector response and p_T of jets accurately. The jet energy can be calibrated using events in which a jet is balanced against a photon or Z boson, but only up to moderate p_T. The multi-jet balance method allows for the calibration of high p_T jets using events in which a single high-p_T jet is recoiling against a system already calibrated jets. The in-situ calibration is a technique for measuring the difference in data and MC jet response and applying a calibration factor until the modeling reaches good agreement.