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The mean number of pile-up jets within |η| < 2.1 that pass various cuts on the reconstructed LCW-scale jet pT, versus the mean number of pile-up interactions per bunch crossing (< μ >). In addition to applying the average offset correction, these jets were required to match hard-scatter track jets of pT > 5 GeV (track-jet confirmed), which rejects a large fraction of pile-up jets. A power law was used to extrapolate the pile-up jet multi plicity to <μ> = 150. Since these extrapolations are based on only two data points each, there is a very large uncertainty in the extrapolated pile-up jet multiplicity.

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The minimum LCW-scale pT cut versus pile-up jet multiplicity extrapolated to <μ> = 150. The data points are fit using an inverse power law. If an analysis requires fewer than 10 % of events to contain one or more pile-up jets, then a minimum pT of approximately 45 GeV would be necessary in the absence of track-jet confirmation. By using track-jet confirmation, it is possible to lower the minimum pT to approximately 25 GeV.

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The jet energy resolution (σ(pT)/pT) measured for anti-kt jets with R = 0.4 within |η|<0.8, versus the true jet pT, in the EM+JES calibration. The data points are fit with the function σ(pT)/pT = √(N^2 /pT^2+ S^2/pT + C^2), where N, S and C are the noise, stochastic and constant terms in the resolution. The resolution is measured for samples with different values of <μ>, the mean number of pile-up interactions per bunch crossing. The noise term increases with <μ> , while the fitted value for S is constant within errors and C is kept fixed to its value for <μ> = 0.

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Noise term (N) of the jet energy resolution versus the mean number of pile-up interactions per bunch crossing (<μ>). N is obtained from the fits to the jet energy resolution measured on anti-kt jets of R = 0.4 within |η|<0.8 in the EM+JES calibration. The value of N is reduced by applying the jet areas correction. A linear fit is used to extrapolate the value of N to <μ> = 150, which is 14 GeV for the average offset and 8 GeV when the jet areas correction is applied.

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