TeV-scale jet energy calibration using multijet events including close-by jet effects at the ATLAS experiment

With the large number of proton-proton collisions delivered by the Large Hadron Collider at a centre-of-mass energy of $\sqrt{s}=7$ TeV in 2011, it became possible to probe the jet transverse momentum (pT) scale beyond the TeV range in events with multijet production. The jet energy scale (JES) uncertainty, which is one of the most important sources of systematic uncertainties for new physics searches at high pT, is evaluated using in-situ techniques based on the pT balance in events with a photon or $Z$ boson as well as in dijet events. Exploiting the pT balance technique between a system of low-pT jets and a leading jet at high pT in multijet events, with the calibration (provided by the gamma-jet and Z+jet events) applied to the low-pT jets, allows the extension of the in-situ determination of JES calibration and uncertainty to the TeV-scale. Results are presented for the JES uncertainty using the multijet balance technique based on the ATLAS data collected in 2011 corresponding to an integrated luminosity of 4.7 fb$^{-1}$. Effects on the JES uncertainty due to the presence of nearby jets are also studied. The JES uncertainty is determined to be 2.0-3.0%, considering the uncertainties associated with the multijet pT balance method and nearby jet effects, for a jet pT between 0.5 and 1.2 TeV.