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Photon + jet Events from Alpgen vs Pythia in CMSSW 1_6_7

Photon + jet Events from Alpgen vs Pythia in CMSSW 1_6_7. Michael Anderson Kira Grogg, Christos Lazaridis University of Wisconsin April 10, 2008. Datasets. Both datasets had to pass triggers Normalized datasets to 100 pb -1 Pythia normalized by CSA07EventWeightProducer

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Photon + jet Events from Alpgen vs Pythia in CMSSW 1_6_7

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  1. Photon + jet Events from Alpgen vs Pythia in CMSSW 1_6_7 Michael AndersonKira Grogg, Christos Lazaridis University of Wisconsin April 10, 2008

  2. Datasets • Both datasets had to pass triggers • Normalized datasets to 100 pb-1 • Pythia normalized by CSA07EventWeightProducer • ALPGEN normalized by hand To put Alpgen Samples through trigger filter in cfg: include "JetMETAnalysis/JetSkims/data/photonjets_Sequences.cff" sequence triggers = { singlePhotonHLTFilter & singleRelaxedPhotonHLTFilter & singlePhotonHLTFilter12 } path p = {triggers,myanalyzer}

  3. CSA07EventWeightProducer From the weight producer: • The weight producer looks for 3 processes for “photon + jet” • So I selected for only those events

  4. Generated Jet • Number of Generated Jets (iterativeCone5GenJetsPt10)with • pt > 20 GeV • No other cuts Events/bin GeV

  5. Generated Photon Et • Highest Et Generated photon • Remember: events went through trigger filters • Why the bumps in the pythia samples? Events/bin GeV

  6. Generated Photon  and   • Dips in  due to gap between barrel & endcap so harder to reconstruct. 

  7. Next Steps • With Kira, examine Pythia vs Alpgen in W/Z + Jets • Begin looking at reconstruction level photons & jets • I’ve been talking to Alexey (Oleksiy) Atramentov in the Photon Identification group and pointed me to qcd samples. These are dijet events where one or two jets were preselected at Pythia level to have leading pi0 - so I can begin looking at jets faking photons

  8. the ugly details

  9. Generated Objects • From each event, selected: • Highest Et  with • Et > 20 GeV • || < 2.5 • Highest pt jet with • pt > 20 GeV • 2.5 <  < 3.8 • Used genParticleCandidatesand iterativeCone5GenJetsPt10 

  10. Photon R to Jet • Between generated and jet • Jet with • Pt > 20 GeV • 2.5 <  < 3.8 Events/bin R

  11. Generated Jet Pt Events/bin GeV

  12. Generated Jet  and   

  13. W/Z + Jet Datasets

  14. +jet Datasets Cross-section (pb)69327.91558.992.016.34.12.2 • Alpgen: • Cross sections from AlpgenSummer07 • Pythia: • Cross sections from CSA07EventWeightProducer /ph1j_20_60-alpgen/CMSSW_1_6_7-CSA07-1201165474/RECO /ph1j_60_120-alpgen/CMSSW_1_6_7-CSA07-1202106391/RECO/ph1j_120_180-alpgen/CMSSW_1_6_7-CSA07-1200559977/RECO /ph1j_180_240-alpgen/CMSSW_1_6_7-CSA07-1200560452/RECO/ph1j_240_300-alpgen/CMSSW_1_6_7-CSA07-1200560032/RECO /ph1j_300_7000-alpgen/CMSSW_1_6_7-CSA07-1203060287/RECO /CSA07AllEvents/CMSSW_1_6_7-CSA07-Gumbo-B1-PDAllEvents-Skims1-photonjets_AODSIM/USER

  15. CSA07EventWeightProducer Handle<double> genCrossSect; evt.getByLabel( "genEventRunInfo", "PreCalculatedCrossSection", genCrossSect); cross_section = *genCrossSect; . . . // photon + jets if ( processID == 14 || processID == 18 || processID == 29 ) { if (pthat > 0 && pthat < 15) { (*weight) = cross_section / 0.3E+06;} if (pthat > 15 && pthat < 20) { (*weight) = cross_section / (0.52E+06); } if (pthat > 20 && pthat < 30) { (*weight) = cross_section / (0.6E+06); } if (pthat > 30 && pthat < 50) { (*weight) = cross_section / (0.51E+06); } if (pthat > 50 && pthat < 80) { (*weight) = cross_section / (0.52E+06); } if (pthat > 80 && pthat < 120) { (*weight) = cross_section / (0.53E+06); } if (pthat > 120 && pthat < 170) { (*weight) = cross_section / (0.56E+06); } if (pthat > 170 && pthat < 300) { (*weight) = cross_section / (2.0E+05); } if (pthat > 300 && pthat < 500) { (*weight) = cross_section / (3.0E+04); } if (pthat > 500 && pthat < 7000) { (*weight) = cross_section / (3.0E+04); } }

  16. Weighing Events • Used CSA07EventWeightProducer by Filip Moortgat to get event weights in skims https://twiki.cern.ch/twiki/bin/view/CMS/CSA07GeneratorInformation

  17. CSA07EventWeightProducer • When different processes get mixed together into a big soup, they cannot all go in with their proper cross sections (we would only have QCD), so some processes are reduced with respect to others. To compensate for this reduction, a "weight" can be given to each event. In an analysis, this weight should be included when calculating numbers of events of a given process passing a certain selection, or when plotting a certain event variable integrated over various processes. • In principle, the "event weight" is given by the cross section times luminosity divided by the number of events of a given process that are in the soup. When a generator level filter has been applied, this artificially enhances the (effective) cross section, so the event weight should be multiplied by the filter efficiency. • In practice, for the CSA07 soup, the calculation of the event weights is non-trivial. The number of events of every process that actually make it into the soup has to be exactly known. Some processes are overlapping (e.g. Min Bias contains also soft QCD) and care needs to be taken to avoid double counting.

  18. Photon + Jet Processes Pythia Alpgen Only selecting these processes from skim using processID

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