Measurement of large radius jet mass reconstruction performance at $\sqrt{s}=8$ TeV using the ATLAS detector

This note presents a measurement of the jet mass scale and jet mass resolution uncertainty for large radius jets using the full $\sqrt{s}=8$ TeV dataset from the ATLAS experiment. Large radius jets are calibrated so that on average the reconstructed jet transverse momentum is the same as the corresponding particle-level jet transverse momentum in simulation. The ratio of the reconstructed jet mass to the particle-level jet mass is the jet mass response. The mean response is the jet mass scale and the standard deviation of the jet mass response distribution is the jet mass resolution. The uncertainty on these quantities is measured by fitting the $W$ boson resonant peak in the large radius jet mass spectrum from lepton plus jets $t\bar{t}$ events in both data and Mont Carlo. Large radius jets with $p_\text{T} > 200$ GeV and $|\eta| < 2.0$ are used in this study. Two fitting procedures are used and give comparable results. For the more precise method, the ratio between the data and the Monte Carlo simulation is $1.001\pm 0.004 \text{(stat)}\pm 0.024\text{(syst)}$ for the jet mass scale and $0.96\pm 0.05\text{(stat)}\pm 0.18\text{(syst)}$ for the jet mass resolution.