ElectronIDRun2 < Main

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---+!! Efficiency and fake rate of the cut-based electron ID for Run 2.

---++ Samples

Signal samples from the CSA production can be found in [[https://cmsweb.cern.ch/das/][DAS]], by typing in the query window:
   * dataset = /RSGravToZZ*/*Spring14dr*/AODSIM

To implement the cut-based electron identification we produced private MINIAODSIM samples with few events (100K), using the common ID and Isolation Toolkit [[https://twiki.cern.ch/twiki/bin/viewauth/CMS/CommonIDAndIsolationFW][CITK]]. 

To access the private samples from lxplus, you have to obtain a valid grid proxy (=voms-proxy-init --voms cms=). The =process.source= in your configure file should look like the following: 

<verbatim>
process.source = cms.Source("PoolSource",
    fileNames = cms.untracked.vstring('root://cmsxrootd.fnal.gov//store/user/jruizvar/RSGravToZZ/M1000/RSGravToZZ_kMpl01_M-1000_Tune4C_13TeV-pythia8_MINIAODSIM_PU20bx25_1.root')
)
</verbatim>

---++ Matching categories

MINIAODSIM samples contain information about generated and reconstructed particles. Our matching algorithm identifies the closest genElectron for every recoElectron, as well as the particle ID of the genElectron's ancestor. 

<br /> <img width="300" alt="deltaR.png" src="%ATTACHURLPATH%/deltaR.png" height="300" />

The *deltaR and PID matching* allows to define four categories as described in the following table:

| *1* | ==Unmatched== | deltaR(closest gen electron, reco electron) > 0.2 |
| *2* | ==Prompt electron== | deltaR(closest gen electron, reco electron) < 0.2  (without ancestor) |
| *3* | ==True electron from tau== | deltaR(closest gen electron, reco electron) < 0.2 AND  (ancestor PID == 15) |
| *4* | ==True electron from Z== | deltaR(closest gen electron, reco electron) < 0.2 AND  (ancestor PID == 23) |
| *5* | ==Anything else== | What remains from above |

---++ Efficiency and fake rate

The efficiency is the number of signal electrons passing the ID divided by the total. The fake rate was estimated in a similar way but using the non-signal electrons. 

<br /> <img width="600" alt="formulas.png" src="%ATTACHURLPATH%/formulas.png" height="170" />

To access the [[https://cmssdt.cern.ch/SDT/doxygen/CMSSW_7_1_7/doc/html/d2/d1f/classpat_1_1Electron.html#aa0fbe7bf4bacf8035991013a67e1a40e][electronID]], which is a member function of the =pat::Electron= class, we used a line like the following:

=int passID = ( el->electronID("cutBasedElectronID-CSA14-PU20bx25-V0-standalone-veto") > 0.5 );=

---++ Working points

The cut-based electron identification recommended by EGM for Run 2 analyses, determines four working points: *veto*, *loose*, *medium*, and *tight*. A detailed description [[https://twiki.cern.ch/twiki/bin/viewauth/CMS/CutBasedElectronIdentificationRun2][here]].

---++ Isolation

Particle flow isolation with delta beta correction is calculated as follows:

<verbatim>
    reco::GsfElectron::PflowIsolationVariables pfIso = el->pfIsolationVariables();
    absiso = pfIso.sumChargedHadronPt + std::max(0.0 , pfIso.sumNeutralHadronEt + pfIso.sumPhotonEt - 0.5 * pfIso.sumPUPt );
    relIsoWithDBeta = absiso/pt;
</verbatim>

Internally, the isolation variables use the standard recommended cone size =deltaR = 0.3=. Details [[https://twiki.cern.ch/twiki/bin/viewauth/CMS/EgammaCutBasedIdentification][here]].

  * Electron isolation after different cut-based selections <br /> <img width="1300" alt="iso.png" src="%ATTACHURLPATH%/iso.png" height="600" />

---++ Preliminary results

To estimate the efficiency and fake rate of the electron identification, we classified the electrons according to its matching category and the *passID* associated to the *cutBasedElectronID-CSA14* working points.

The classification for each working point is displayed as a TH2 histogram with two bins in the Y axis associated to the passID variable, and four bins in the X axis corresponding to the matching categories. The number of entries inside each box of the histogram indicates the number of electrons in a given matching category with a given passID.   

   * Electron classification, global efficiency, and fake rate using sample RSGravToZZ 1 TeV <br /> <img width="1083" alt="RSGravToZZ-M1000_matchId.png" src="%ATTACHURLPATH%/RSGravToZZ-M1000_matchId.png" height="750" />

   * Electron classification, global efficiency, and fake rate using sample RSGravToZZ 4.5 TeV <br /> <img width="1083" alt="RSGravToZZ-M4500_matchId.png" src="%ATTACHURLPATH%/RSGravToZZ-M4500_matchId.png" height="750" />

Efficiency and fake rate as function of genElectron's pT and eta are shown below:

   * Efficiency and fake rate as function of genElectron's pT <br /> <img width="1300" alt="eff_pt.png" src="%ATTACHURLPATH%/eff_pt.png" height="600" />

   * Efficiency and fake rate as function of genElectron's eta <br /> <img width="1300" alt="eff_eta.png" src="%ATTACHURLPATH%/eff_eta.png" height="600" />

   * Efficiency as function of deltaR(genElectron1, genElectron2) <br /> <img width="1300" alt="eff_dR.png" src="%ATTACHURLPATH%/eff_dR.png" height="300" />

   * Efficiency as function of deltaR(genElectron1, genElectron2) zoom in the low deltaR region <br /> <img width="1300" alt="eff_dR_zoom.png" src="%ATTACHURLPATH%/eff_dR_zoom.png" height="300" />


---++ Software

The analyzer developed for these studies is attached below:
   * [[https://www.sprace.org.br/twiki/pub/Main/ElectronIDRun2/MCTruth_RSGravToZZ_M1000.py.txt][Configure file]]
   * [[https://www.sprace.org.br/twiki/pub/Main/ElectronIDRun2/EDBRGenStudies.cc.txt][EDAnalyzer]]
   * [[https://www.sprace.org.br/twiki/pub/Main/ElectronIDRun2/BuildFile.xml.txt][BuildFile]]

---++ Ongoing work

In addition to the cut-based electron ID, we plan to use the Multivariate Electron Identification for Run 2. Instruction for running the *MVA* electron ID in the following [[https://twiki.cern.ch/twiki/bin/viewauth/CMS/MultivariateElectronIdentificationRun2][link]].

---++ Comments

%COMMENT%

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who	Comment
txt	BuildFile.xml.txt	r1	manage	0.3 K	2014-09-29 - 09:29	JoseRuiz	BuildFile for ElectronID studies
txt	EDBRGenStudies.cc.txt	r2 r1	manage	9.1 K	2014-09-29 - 15:55	JoseRuiz	Analyzer for ElectronID studies
txt	MCTruth_RSGravToZZ_M1000.py.txt	r1	manage	2.7 K	2014-09-29 - 09:32	JoseRuiz	Configure file for ElectronID studies and sample RSGravToZZ-M1000
txt	MCTruth_RSGravToZZ_M4500.py.txt	r1	manage	2.8 K	2014-09-29 - 09:21	JoseRuiz	Configure file for ElectronID studies
png	RSGravToZZ-M1000_matchId.png	r2 r1	manage	35.3 K	2014-09-29 - 08:49	JoseRuiz	Classification of electrons in sample RSGravToZZ-M1000
png	RSGravToZZ-M4500_matchId.png	r2 r1	manage	35.2 K	2014-09-29 - 08:50	JoseRuiz	Classification of electrons in sample RSGravToZZ-M4500
png	deltaR.png	r2 r1	manage	21.2 K	2014-09-29 - 11:32	JoseRuiz	DeltaR matching
png	eff_dR.png	r2 r1	manage	41.4 K	2014-09-29 - 16:00	JoseRuiz	Efficiency as function of deltaR(genElectron1, genElectron2)
png	eff_dR_zoom.png	r1	manage	39.0 K	2014-09-30 - 13:33	JoseRuiz	Efficiency as function of deltaR(genElectron1, genElectron2) zoom in the low deltaR region
png	eff_eta.png	r3 r2 r1	manage	73.9 K	2014-09-29 - 08:57	JoseRuiz	Efficiency and fake rate as function of genElectron's eta
png	eff_pt.png	r4 r3 r2 r1	manage	72.2 K	2014-09-29 - 11:43	JoseRuiz	Efficiency and fake rate as function of genElectron's pT
png	formulas.png	r2 r1	manage	70.2 K	2014-09-29 - 08:42	JoseRuiz	Efficiency and fake rate formulas
png	iso.png	r4 r3 r2 r1	manage	47.3 K	2014-09-29 - 09:35	JoseRuiz	Electron isolation with delta beta correction

Topic revision: r15 - 2014-10-08 - JoseRuiz

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