Jets in Standard Reconstruction

Several jet collections are build by the reconstruction, varying
  • Input to jet finder : Calorimeter Tower, topological clusters or truth particles
  • Jet Finder algorithm : Cone or Kt
  • Main parameter of the jet finder
The collections are saved in ESD and AOD as JetCollection objects (in ESD) or ParticleJetContainer objects (in AOD).
A typical name (or key) for a JetCollection is '!Cone7H1TowerJets' and all names follow this pattern : (algorithm type)(main parameter)(calibration method)(input type)Jets.

More details on each aspects :

  • Algorithm type
    • Cone : the seeded cone algorithm. Default parameters : Radius=0.4 or 0.7, Pt of seeds = 1 GeV, split/merge fraction=0.5
    • Kt : the inclusive kt algorithm (fast version), D parameter =0.4 or 0.6
  • Main parameter : corresponds to Radius*10 for cone algs or D*10 for Kt algs.
  • Input type
    • Towers : means calorimeter towers at EM scale
    • Topo : means topological clusters. If calibration type is H1, using clusters at EM scale. Else if calibration is LC, using calibrated TopoClusters
  • calibration method
    • H1 : means the 'global' H1-style calibration is applied on jets after jet finding. The H1 calibration is specific for each type of jet finder and each value of the main parameter. For example, the set of corrections for Cone7H1TowerJets is different than for Cone7H1TopoJets and for Cone4H1TowerJets.
    • LC : means Local Calibration. It applies only to jets build from topo clusters. In this case the jet finder uses the local calibrated topoclusters (which include hadronic calibration, dead matrerial correction and after 13.0.1 out-of-cluster corrections).

Currently only H1 calibrated jets are written out in ESD and AOD.
In AOD the ParticleJetContainer name are the same than in ESD except that 'Jets' is replaced by 'ParticleJets'

-- PierreAntoineDelsart - 16 May 2007

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Topic revision: r1 - 2007-05-16 - PierreAntoineDelsart
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