Monte Carlo Calibration and Combination of In-situ Measurements of Jet Energy Scale, Jet Energy Resolution and Jet Mass in ATLAS

The various stages in the final Run-1 jet energy scale calibration in the ATLAS detector at the Large Hadron Collider are described. The Monte Carlo based calibration is discussed for both small ($R=0.4$ or $0.6$) and large ($R\ge1.0$) radius jets and the final combination of various in-situ measurements and the resultant jet energy scale uncertainty is presented. An uncertainty on the jet energy calibration of less than 1% is acheived for small-radius jets with $|\eta|<0.8$ and $150<p_{\rm T}<1500$ GeV. The mass scale calibration of large radius jets is also discussed with its associated uncertainties which are around 4% in the central region for jets with $200<p_{\rm T}<2000$ GeV. Next, two novel methods to measure the noise component of the jet energy resolution in small radius jets are discussed, which have a measurement precision of 20%. Finally, the combination of in-situ measurements of the jet energy resolution for small jets and the associated uncertainties are presented with a total jet energy resolution uncertainty of 1% above 100 GeV and less than 3% at 20 GeV. The joint effect of the jet energy resolution combination and direct noise measurements allows a first extraction of distinct noise, stochastic and constant resolution terms.