Abstract
The jet energy scale, jet energy resolution, and their systematic uncertainties are measured for jets reconstructed with the ATLAS detector in 2012 using proton–proton data produced at a centre-of-mass energy of 8 TeV with an integrated luminosity of 20 , hbox {fb}^{-1}. Jets are reconstructed from clusters of energy depositions in the ATLAS calorimeters using the anti-k_t algorithm. A jet calibration scheme is applied in multiple steps, each addressing specific effects including mitigation of contributions from additional proton–proton collisions, loss of energy in dead material, calorimeter non-compensation, angular biases and other global jet effects. The final calibration step uses several in situ techniques and corrects for residual effects not captured by the initial calibration. These analyses measure both the jet energy scale and resolution by exploiting the transverse momentum balance in gamma + jet, Z + jet, dijet, and multijet events. A statistical combination of these measurements is performed. In the central detector region, the derived calibration has a precision better than 1% for jets with transverse momentum 150 , hbox {GeV} < p_{{mathrm {T}}}< 1500 GeV, and the relative energy resolution is (8.4pm 0.6)% for p_{{mathrm {T}}}= 100 , hbox {GeV} and (23pm 2)% for p_{{mathrm {T}}}= 20 , hbox {GeV}. The calibration scheme for jets with radius parameter R=1.0, for which jets receive a dedicated calibration of the jet mass, is also discussed.
Highlights
Collimated sprays of energetic hadrons, known as jets, are the dominant final-state objects of high-energy proton–proton interactions at the Large Hadron Collider (LHC) located at CERN
To propagate the uncertainty to RMJB, all input components are individually varied by ±1σ and the full iterative analysis procedure is repeated for each such variation
The uncertainty due to Monte Carlo (MC) modelling of multijet events is estimated from the symmeterized envelope of multijet balance (MJB) corrections obtained by comparing the nominal results obtained from Sherpa with those obtained from Powheg + Pythia8, Pythia8, and Herwig++
Summary
Collimated sprays of energetic hadrons, known as jets, are the dominant final-state objects of high-energy proton–proton ( pp) interactions at the Large Hadron Collider (LHC) located at CERN. Calorimeter jets, which are reconstructed from calorimeter energy depositions, are calibrated to the energy scale of jets created with the same jet clustering algorithm from stable interacting particles. This calibration accounts for the following effects:. 4. Section 5 describes the global sequential calibration method, which exploits information from the tracking system (including the muon chambers) and the topology of the energy depositions in the calorimeter to improve the JES uncertainties and. 6. The methods based on the pT balance between a jet and a well-calibrated photon or Z boson are discussed, while the study of the balance between a high- pT jet and a system of several low- pT jets is presented in Sect.
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