Temporary EgammaAnalysis/ElectronTools Twiki

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Added new regression and new combination

Regressions are used to improve the determination of the electron momentum wrt the reco determination. In addition energy scale corrections (or additional smearing for the MC) are applied.

Two modules are run sequentially: a module to run the energy regression and a module to run the scale corrections and the E-p combination. In the most recent version (default version), the E-p combination is also performed using a dedicated regression instead of the cut based algorithm used for HCP2012 and Moriond2013.

Electron energy regression

Two energy regressions are available and can be chosen in the python configuration:

  • The new regression using additional information from subclusters, which is the default one (regression type 2)
  • The original one used for HCP2012 and Moriond2013 (regression type 1)

In order to setup the regression energy producer one has to modify the following parameters:

process.eleRegressionEnergy.energyRegressionType = cms.uint32(1) 
Putting this value to 1 gives original regression; 2: new regression w/ subcluster information. NB: this setting is strongly connected with the following one, input file path. Please set it correctly

  • #the proper verification of regression type and input file compatibility should be added in the coming code release

process.eleRegressionEnergy.regressionInputFile = cms.string("EGamma/EGammaAnalysisTools/data/eleEnergyRegWeights_V1.root") 
This is input file containing the BDTs needed by the regression. Here is the list of files with description:


  • eleEnergyReg2012Weights_V1.root - File with weights corresponding to the regression type 1 used at Moriond 2013.
  • eleEnergyRegWeights_WithSubClusters_VApr15.root - File with weights corresponding to the regression type 2.


  • eleEnergyReg2011Weights_V1.root - File with weights corresponding to the regression type 1 recomputed in December 2012.
  • eleEnergyReg2011Weights_WithSubClusters_VApr23.root - File with weights corresponding to the regression type 2.

Electron energy scale corrections and smearing

Energy scale correction factors and smearing for the MC are derived following the technique used for the Hgg analysis (Shervin et al.). The module below allows to correct the scale in data and smear the MC with the best known factors to date. It consists in applying correction and smearing factors by category to the reconstructed electrons. It does not performs a full rereco of the GsfElectrons, but only recompute the final electron momentum value. In latest version MC smearing is also propagated to the electron combined momentum error.

Currently the scales and smearing for the regression energy type 1 (as used at Moriond) are implemented. One can find the values at https://twiki.cern.ch/twiki/bin/view/CMS/ECALELF.

  • correctionsType
correctionsType=cms.int32(0) Don't apply any corrections and combination
correctionsType=cms.int32(1) Apply scale corrections and smearing for regression energy type 1
correctionsType=cms.int32(2) Apply scale corrections and smearing for regression energy type 2. Numbers aren't implemented yet
correctionsType=cms.int32(3) Apply scale corrections and smearing for standard ecal energy. Numbers aren't implemented yet
  • lumiRatio
lumiRatio=cms.double(0.0) Apply MC smearing for 2012 HCP dataset. Use just in case crosscheck works for HCP data.
lumiRatio=cms.double(1.0) Apply MC smearing for 2012D dataset. Use just in case rerunning 2012D data only.
lumiRatio=cms.double(x) Apply MC smearing for the mixture of 2012HCP and 2012D data. lumiRatio should be setted to the fraction of added to HCP2012 data w.r.t. to the HCP data. For example, when runnung module for integrated luminosity 19.6 fb-1, lumiRatio should be (19.6-12.2)/12.2=0.607

Electron energy-momentum combination

In order to achieve the best accuracy and performance on electron momentum estimation the energy from ECAL and momentum from tracker are combined. There're now two different algorithms:

  • cut-based, used at the HCP'2012 and Moriond'2013
  • new, regression-based

In order to setup the config file you have to indicate the following:

  • combinationType
combinationType=cms.int32(0) Don't apply combination. Final momentum is combination between uncorrected electron.ecalEnergy() and track momentum.
combinationType=cms.int32(1) Apply old (cut-based) combination with smeared/corrected regression energy
combinationType=cms.int32(2) Apply old (cut-based) combination with unsmeared/uncorrected regression energy
combinationType=cms.int32(3) Apply new (regression) combination with smeared/corrected regression energy

  • # Are we going to decouple the file with weights for regression energy energy estimation and for combination?

Software instructions


Latest tag: cvs co -r V00-00-02 EgammaAnalysis/ElectronTools


Latest tag: cvs co -r V00-00-02-44X EgammaAnalysis/ElectronTools
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Topic revision: r1 - 2013-04-25 - MykhailoDalchenko
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