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JetEtmissApproved2013HighMuJets

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ρ is calculated using kt R=0.4 jets reconstructed from locally calibrated (LCW) topoclusters within |η|<2. The density calculation is with respect to the Voronoi area of the jets as defined in JHEP 0804 (2008) 005. Topoclusters are an attempt to reconstruct three-dimensional energy deposits in the calorimeter and are built using a nearest-neighbor algorithm that clusters calorimeter cells with energy significance (|Ecell|/σ) >4 for the seed, >2 for neighbors, and >0 at the boundary. Ecell is calibrated using informaton derived from test beam and detailed GEANT4 simulatons (EM scale) and σ is the sum in quadrature of the electronic and expected pileup noise, as described in Sec. 10.5.2 of JINST 3 (2008) S08003. Topoclusters can be further calibrated using local information (LCW) as described in Nucl. Instrum. Meth. A 531 (2004) 481. The pileup noise used in topoclustering is chosen to match the pileup conditons. Pileup is simulated by overlaying GEANT4 simulated events from PYTHIA (v6.4) including non-diffractive and diffractive events.

Truth jets are built using stable particles from the hard-scatter collision excluding muons and neutrinos. A pileup-jet is defined as a reconstructed jet that is not closely matched in ΔR to a truth jet. We define a close match as ΔR<0.6, and only truth jets with pT >5 GeV are considered.

The mean pileup jet multiplicity as a function of the number of truth vertices Nvtx in events with an average number of interactions per bunch crossing (<μ>) of 140. The closed circles (squares) represent the mean number of pileup jets with pT >20 GeV (solid markers) and 40 GeV (open markers) before (magenta) and after (blue) pileup subtraction using the event-by-event median pT density, ρ. Pileup subtraction significantly reduces the mean number of pileup jets per event.


[pdf]
The mean pileup jet multiplicity as a function of the number of truth vertices Nvtx in events with an average number of interactions per bunch crossing (<μ>) of 140. The closed circles (squares) represent the mean number of pileup jets with pT >20 GeV before (magenta) and after (blue) pileup subtraction using the event-by-event median pT density, ρ. Pileup subtraction significantly reduces the mean number of pileup jets per event.
[pdf]
The mean pileup jet multiplicity as a function of the number of truth vertices Nvtx in events with an average number of interactions per bunch crossing (<μ>) of 140. The closed squares (squares) represent the mean number of pileup jets with pT >40 GeV before (magenta) and after (blue) pileup subtraction using the event-by-event median pT density, ρ. Pileup subtraction significantly reduces the mean number of pileup jets per event.
[pdf]


Major updates:
-- MichaelBegel - 26-Jul-2013

Responsible: MichaelBegel
Subject: public

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Topic revision: r3 - 2013-07-30 - MichaelBegel
 
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