[Mean number of pileup jets vs mean number of interactions] The mean number of pileup jets within η < 2.1 that pass various cuts on the reconstructed LCWscale jet pT, versus the mean number of pileup interactions per bunch crossing (< μ >). A correction, dependent on the number of reconstructed primary vertices and <μ>, was applied to the jets in order to subtract the average pT offset induced by pileup. A power law was used to extrapolate the pileup jet multiplicity to <μ> = 150. Since these extrapolations are based on only two data points each, there is a very large uncertainty in the extrapolated pileup jet multiplicity.

[Mean number of pileup jets vs mean number of interactions]
The mean number of pileup jets within η < 2.1 that pass various cuts on the reconstructed LCWscale jet pT, versus the mean number of pileup interactions per bunch crossing (< μ >). In addition to applying the average offset correction, these jets were required to match hardscatter track jets of pT > 5 GeV (trackjet confirmed), which rejects a large fraction of pileup jets. A power law was used to extrapolate the pileup 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 pileup jet multiplicity.

[Pt cut vs pileup jet multiplicity]
The minimum LCWscale pT cut versus pileup 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 pileup jets, then a minimum pT of approximately 45 GeV would be necessary in the absence of trackjet confirmation. By using trackjet confirmation, it is possible to lower the minimum pT to approximately 25 GeV.

[Jet resolution vs pt]
The jet energy resolution (σ(pT)/pT) measured for antikt 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 pileup 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.

[Noise term vs mu]
Noise term (N) of the jet energy resolution versus the mean number of pileup interactions per bunch crossing (<μ>). N is obtained from the fits to the jet energy resolution measured on antikt 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.

Major updates:
 TancrediCarli  19Jul2012
Responsible: TancrediCarli
Subject: public
I  Attachment  History  Action  Size  Date  Who  Comment 

eps  EM4NvsMuY0.eps  r1  manage  12.6 K  20120719  22:09  TancrediCarli  
png  EM4NvsMuY0.png  r1  manage  16.4 K  20120719  22:09  TancrediCarli  
eps  EM4RinMuBinseta0.eps  r1  manage  19.4 K  20120719  22:09  TancrediCarli  
png  EM4RinMuBinseta0.png  r1  manage  21.9 K  20120719  22:09  TancrediCarli  
eps  meanTJCVsMu_ETA0.eps  r1  manage  16.5 K  20120719  22:09  TancrediCarli  
png  meanTJCVsMu_ETA0.png  r1  manage  19.4 K  20120719  22:09  TancrediCarli  
eps  meanVsMu_ETA0.eps  r1  manage  16.1 K  20120719  22:09  TancrediCarli  
png  meanVsMu_ETA0.png  r1  manage  19.0 K  20120719  22:09  TancrediCarli  
eps  ptMinVsMean_ETA0.eps  r1  manage  12.6 K  20120719  22:09  TancrediCarli  
png  ptMinVsMean_ETA0.png  r1  manage  18.3 K  20120719  22:09  TancrediCarli 