Two-lepton/four-lepton analysis example of CMS 2010 open data

External links

https://github.com/ayrodrig/OutreachExercise2010

Data selection

An event selection is applied in the two analysis cases:

1. In the Z analysis at least two leptons with opposite charge, with invariant mass ”mll” between 12 GeV and 120 GeV are required. The pair with the invariant mass closest to the Z boson mass is selected as the Z candidate.
2. In the ZZ analysis two Z candidates are required, and for both candidates, two leptons with opposite charge are required. The first Z candidate is required to have higher lepton momentum: 20 GeV for the first lepton and 10 GeV for the second lepton. The invariant mass is required to be in the range 40 GeV to 120 GeV. The second candidate is required to have an invariant mass higher then 4 GeV. The first candidate is the one with the invariant mass closest to the Z boson mass.

Selection criteria for electron candidates:

• pT > 7 GeV and |η| < 2.5;
• Distance between the electron z-vertex and the interaction z-vertex < 0.2 cm;
• Transverse impact parameter w.r.t. the beam spot < 0.04 cm;
• Symmetrised impact parameter w.r.t. the beam sport < 4 cm;
• Photon conversion rejection: number of lost hits in the tracker < 1;
• Electron identification: eIDLoose;
• Electron Isolation depends on the η region, regions with 1.44 < η 0.09; electron.dr03EcalRecHitSumEt()/electron.pt() > 0.07; and electron.dr03HcalTowerSumEt()/electron.pt() > 0.10. If η > 1.57: electron.dr03TkSumPt()/electron.pt() > 0.04; electron.dr03EcalRecHitSumEt()/electron.pt() > 0.05; and electron.dr03HcalTowerSumEt()/electron.pt() > 0.025. Each component is computed from Isodeposits in a cone of 0.3 around the electron direction.

Selection criteria for muon candidates:

• pT > 5 GeV and |η| < 2.4;
• Distance between the muon z-vertex and the interaction z-vertex < 0.2 cm;
• Is a GlobalMuon and TrackerMuon;
• Number of valid hits in the inner tracker > 10;
• χ2 /ndo f < 10 for the global muon fit;
• Transverse impact parameter w.r.t. the beam spot < 0.02 cm;
• Symmetrised impact parameter w.r.t. the beam sport < 4 cm;
• Relative Muon Isolation (RMI) < 0.15, with RMI = (ChargedHadronIso + NeutralHadronIso + PhotonIso)/pT(µ)

Validation

The input files contain only the validated runs. For user validation of the analysis step, compare the result to the expected output file.

CMS list of validated runs Cert_136033-149442_7TeV_Apr21ReReco_Collisions10_JSON_v2.txt

How can you use this?

See the run instructions in

GitHub

Source code repository