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Study of QCD background

This document details the findings from Shilei Zang's study presented at the GMSB Meeting on May 30, 2008, focusing on Quantum Chromodynamics (QCD) and establishing a control sample. Key questions addressed include the isolation space's adequacy between triggers and analyses, the dependence of MET shape on isolation cuts, and additional criteria for control samples. The study emphasizes the feasibility of obtaining sufficient QCD control events with specific isolation criteria, while analyzing the characteristics of di-photon samples under various conditions. Conclusions underscore the similarities in MET distributions across analyzed samples.

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Study of QCD background

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  1. Study of QCD background ShileiZang University of Colorado, Boulder GMSB Meeting, 30 May 2008

  2. Questions for QCD control sample • Do we have enough isolation space between trigger and analysis to get enough control events? • Does/How the MET shape depends on the isolation cuts? • Any other cuts (shower shape, photon Et, number of jets, ..) to get the control sample? Does/how the MET shape depends on these cuts?

  3. Di-photons sample (standard cuts) • HLT: S, RS, D, RD (the primary datasets: PDPhoton) • Offline Isolation: trkIso<9GeV; HoE<0.1 • Others: Pt1>90GeV; Pt2>30GeV; Eta<1.479 Control sample (test) • Both photons pass loose cuts and at least one photon fails the standard cuts. • trkIsoAll: trkIso<infinite; HoE<0.1 • hcalIsoAll: trkIso<9GeV; HoE<infinite • IsoAll:trkIso<infinite; HoE<infinite • trkIso2: trkIso<20GeV; HoE<0.1 • hcalIso2: trkIso<9GeV; HoE<0.2 • Iso2: trkIso<20GeV; HoE<0.2 • PtAll:Pt1>20GeV; Pt2>20GeV

  4. Gumbo: QCD, Photon+jets (5201.53 evts) • Chowder: W+jet, Z+jet, tt+jet (49.37 evts) • GMSB: GM1e (80.22 evts) Di-photons; 1/fb

  5. trkIsoAll: trkIso<infinite; HoE<0.1

  6. hcalIsoAll: trkIso<9GeV; HoE<infinite

  7. IsoAll: trkIso<infinite; HoE<infinite

  8. PtAll: Pt1>20GeV; Pt2>20GeV

  9. trkIso2: trkIso<20GeV; HoE<0.1

  10. hcalIso2: trkIso<9GeV; HoE<0.2

  11. Iso2: trkIso<20GeV; HoE<0.2

  12. We can get enough events for control sample: trkIsoAll

  13. trkIso Francesco HoE

  14. Summary • We can get enough QCD control events with isolations. • The MET shapes of di-photons and the control sample are roughly same. • We can assume all MET<80GeV is contributed from QCD. • Already added metX, metY, and phoMatched into Rtuple. • I’m reprocessing the soups. Output files will be here: • /pnfs/cms/WAX/resilient/slzang/bkg_study_080529 • Add information of jets into Rtuple (what information?) • Add elec-ID, elec-Iso into Rtuple? • Determine the criteria for the QCD control sample (how?). • Study the variable of Inv-Mass. (it’s promising, see my slides on May 16 GMSB meeting) Thank you!

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