Information Common To All Plots
ρ is calculated using k_{t} 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 threedimensional energy deposits in the calorimeter and are built using a nearestneighbor algorithm that clusters calorimeter cells with energy significance (E_{cell}/σ) >4 for the seed, >2 for neighbors, and >0 at the boundary. E_{cell} 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 nondiffractive and diffractive events.
Truth jets are built using stable particles from the hardscatter collision excluding muons and neutrinos. A pileupjet 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 p_{T} >5 GeV are considered.
The mean pileup jet multiplicity as a function of the number of truth vertices N_{vtx} 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 p_{T} >20 GeV (solid markers) and 40 GeV (open markers) before (magenta) and after (blue) pileup subtraction using the eventbyevent median p_{T} 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 N_{vtx} 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 p_{T} >20 GeV before (magenta) and after (blue) pileup subtraction using the eventbyevent median p_{T} 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 N_{vtx} 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 p_{T} >40 GeV before (magenta) and after (blue) pileup subtraction using the eventbyevent median p_{T} density, ρ. Pileup subtraction significantly reduces the mean number of pileup jets per event. 
[pdf] 
Major updates:
 MichaelBegel  26Jul2013
Responsible: MichaelBegel
Subject: public