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SPS8 Diphoton Analysis Update

SPS8 Diphoton Analysis Update. Daniel Damiani 29 April 2010. Full Simulation SPS8 Point. There is now a full simulation/official production SPS8 point available on the grid mc09_7TeV.114007.SPS8_110_jimmy_susy.merge.AOD.e530_s765_s767_r1207_r1210

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SPS8 Diphoton Analysis Update

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  1. SPS8 Diphoton Analysis Update Daniel Damiani 29 April 2010

  2. Full Simulation SPS8 Point • There is now a full simulation/official production SPS8 point available on the grid • mc09_7TeV.114007.SPS8_110_jimmy_susy.merge.AOD.e530_s765_s767_r1207_r1210 • Different simulation/geometry and reconstruction than the fast sim samples I have generated – still it reveals a problem with Atlfast II that effects this analysis

  3. 7 TeV MC Samples • Most of the 7 TeVmontecarlo has now been redone with the same new simulation and reconstruction version as the full simulation SPS8 point • Some of the old 7 TeV datasets have been deleted, some have not

  4. Object Selections (egamma) • Photons • PT> 20 GeV, eta < 2.5, isem – PhotonTight • Duplicate cluster removal – detlaR < 0.01 • A PT>40 GeV was also tried • Electrons • PT > 20 GeV, eta < 2.5, isem – ElectronLoose • Duplicate cluster removal – detlaR < 0.01

  5. Other Object Selections • Jets • AntiKt4H1TopoJets, Et > 20 GeV, and eta < 2.5 • Muons • isCombinedMuon() • 0<=matchChi2<=100 • pt > 10 GeV && |eta| < 2.5 • Overlap removal • Photons conversions removed from electrons (deltaR – 0.2) • Photons plus electrons of at least loose quality removed from jets (deltaR - 0.4)

  6. Other Definitions • HT is scalar sum of the et of the selected photons, leptons, and jets • NO missing et included • SumET – variable is taken directly from the missing et container in the AOD • The Sum ET variable was used instead of HT (which was used previously) in the following analysis

  7. SumET versus HT

  8. Photon Isolation • Different types of isolation being looked at for the analysis • None • ‘Historical’ - etcone20/et < 0.1 • Official egamma (isem bit 29) • Similar etcone20/et < some value and ptcone20/pt < some other value where those values vary as a function of photon pt and eta • SPS8 Λ=110 Signal efficiency (requiring 2 photons) • No isolation – 51% • ‘Historical isolation – 47% • Egamma isolation – 41% • Looking at several of the background samples the egamma isolation is not always more severe than the historical one

  9. Significances for 100pb-1

  10. Conclusions/Fast Sim Issues • This significance is much lower than previously quoted. This appears to be due to an issue that we discovered with the fast simulation. • Significance for the ‘historical’ iso cut option decreased from 4.1 to 2.7 • The fast sim appears to have an issue with jets in terms of number/pt spectrum which affects the HT variable • The fast sim sample has ~2 times as many jets. • The pt spectrum of the jets in the fast sim is harder • The scalar sum of the et in the jets is not consistent with the sumet in the fast sim (it is in the full sim). • Oddly the sum_et variable is consistent between the fast and full simulation. While the HT is not. • The full HT and sum_et are consistent with each other while for the fast sim the HT is consistently higher

  11. Fast/Full Comparison Plots • Following plots are comparing variables in the fast sim versus full SPS8 Λ=110 TeV point • Looking at the objects in the containers with no cuts applied • MetRef_Finaland AntiKt4H1TopoJets containers were used • Missing ET and photon number and pt spectrum seem consistent between fast and full sim

  12. Jet Number Comparison --- Atlfast II --- Full sim

  13. Jet Pt Spectrum Comparison Normalized to same number of jets --- Atlfast II --- Full sim pt [MeV]

  14. Missing ET Comparison --- Atlfast II --- Full sim MET [MeV]

  15. Sum ET Comparison --- Atlfast II --- Full sim Sum ET [MeV]

  16. Photon PT Comparison --- Atlfast II --- Full sim pt [MeV]

  17. Further Issues • Looking at the fast sim about 13% of the events have a scalar sum of the et of jets that exceeds the sum et • Sum by more than 50 GeV! • For the full simulation only 4 events out of 9987 events have a scalar sum of the jets et that is higher than the sum et variable • Exceeds by ~10 GeV or less • This talk: http://indico.cern.ch/conferenceDisplay.py?confId=89746 seems to show issues with the jets in the fast sim as well

  18. Conclusions • Exclusions above the Tevatron limit are still possible with ~100pb-1 • There appears to be issues with Atlfast II and jets that lead us to previous over-estimate the signal when using the jets to calculate HT • Using cuts based on jets with Atlfast II does not appear safe without validation (note - these Atlfast II samples were made in 15.6.3.6)

  19. Backup

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