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W->eν+jets Update

W->eν+jets Update. Kira Grogg UW-Madison 14 May, 2009. Action Items. Now including Ttbar+jets and Zee+jets backgrounds S/√(S+B) using all backgrounds and all selection cuts Now have W transverse mass cut applied Trying p T dependent electron ID cuts Not sure how to optimize

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W->eν+jets Update

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  1. W->eν+jets Update Kira Grogg UW-Madison 14 May, 2009 K. Grogg, UW-Madison

  2. Action Items • Now including Ttbar+jets and Zee+jets backgrounds • S/√(S+B) using all backgrounds and all selection cuts • Now have W transverse mass cut applied • Trying pT dependent electron ID cuts • Not sure how to optimize • Also checking new recommended electron ID cuts • Given in: http://indico.cern.ch/getFile.py/access?contribId=1&resId=0&materialId=slides&confId=56255 • In process of adjusting PF parameters but still not right • Don’t have new results yet • Need better understanding of PF candidates K. Grogg, UW-Madison

  3. Electron Iso efficiency and S/√(S+B) vs Cut • (Σpt+ΣEcal+ΣHcal)/ETsc < 0.1 • Cones 0.3, 0.4, 0.4 W efficiency QCD efficiency S/√(S+B) • Selection cuts applied: • Electron pT > 20 GeV, • Electron 0 < |η| < 2.4 • excluding gap • Electron robust tight ID • 55 < mT < 105 GeV Sum Isolations UW-Madison

  4. Electron ID efficiency and S/√(S+B) vs Cut (Barrel) W efficiency QCD efficiency S/√(S+B) S/√(S+B) ~550 S/√(S+B) ~220 • Selection cuts applied: • Electron pT > 20 GeV • Electron 0 < |η| < 1.442 • Sum Isolation < 0.10 • 55 < mT < 105 GeV σiηiη H/E Old “tight” cut New “tight” cut S/√(S+B) ~220 S/√(S+B) ~220 Δφin Δηin UW-Madison

  5. Electron ID efficiency and S/√(S+B) vs Cut (endcap) W efficiency QCD efficiency S/√(S+B) S/√(S+B) ~350 S/√(S+B) ~300 • Selection cuts applied: • Electron pT > 20 GeV • Electron 1.56 < |η| < 2.4 • Sum Isolation < 0.10 • 55 < mT < 105 GeV σiηiη H/E Old “tight” cut New “tight” cut S/√(S+B) ~300 S/√(S+B) ~300 Δφin Δηin UW-Madison

  6. Low acceptance for electron ID at low & high pT Cuts are progressive Using old “tight” cuts IDvariable < A Efficiency of σηiηi Efficiency of H/E Efficiency of Δη Efficiency of Δφ K. Grogg, UW-Madison

  7. Profile plots of electron ID variables vs electron pT (Barrel) H/E σiηiη Cut needs to be looser at higher pT Electron pT Electron pT Δηin Δφin Electron pT Electron pT K. Grogg, UW-Madison

  8. Profile plot of isolation sum vs electron pT Can use constant cut: iso sum < A (Don’t lose efficiency at high pT) Sum of all isolations/ET K. Grogg, UW-Madison

  9. Low acceptance for electron ID at low & high pT Cuts are progressive IDvariable < A+B pT Efficiency of σηiηi Efficiency of H/E H/E < 0.009 + 0.00018pT σiηiη < 0.0075 + 0.00009pT PT dependent cuts more efficient, but allow more background too Efficiency of Δη Efficiency of Δφ Δφin < 0.018 + 0.00009pT Δηin < 0.0008 + 0.00009pT K. Grogg, UW-Madison

  10. Low acceptance for isolation sum at low pT After constant electron ID cuts applied Efficiency of sum of all isos Includes Wμν or τν events Electron pT Isolation sum: (Σpt+ΣEcal+ΣHcal)/ETsc < 0.1 K. Grogg, UW-Madison

  11. Low acceptance for isolation sum at low pT After pT dependent electron ID cuts applied Efficiency of sum of all isos Only includes Weν events Electron pT Isolation sum: (Σpt+ΣEcal+ΣHcal)/ETsc < 0.1 K. Grogg, UW-Madison

  12. N-1 Electron Plots using old robust tight ID+isolation cuts H/E σiηiη Electron pT Electron pT Δηin Δφin Electron pT Electron pT K. Grogg, UW-Madison

  13. N-1 Electron Plots using new robust ID+isolation cuts σiηiη Electron pT Electron pT Δηin Δφin Electron pT Electron pT K. Grogg, UW-Madison

  14. N-1 electron isolation plots using robust ID+isolation cuts Cutting on old robust tight ID cut values Cutting on new robust tight ID cut values Efficiency of sum of all isos Efficiency of sum of all isos Electron pT Electron pT K. Grogg, UW-Madison

  15. Comparison of old ID cuts vs new cuts For W+1 jet events New set of ID cuts performs roughly the same before the W transverse mass cut, and better after the transverse mass cut PT dependent cut has good efficiency but higher QCD background – needs better tuning K. Grogg, UW-Madison

  16. MET, W mT Signal and backgrounds Cross sec. normalized 200 pb-1 • Cuts • Electron pT < 20 GeV, |η| < 2.4 • Robust tight ID • Sum isolation (default cones) • One Jet pT > 15 GeV MET W mT Signal is visible over background UW-Madison

  17. Conclusions / Next Steps • There is a linear pT dependence of electron ID cuts • Most dramatic for σiηiη • N-1 plots don’t show high pT dependence • Attempt at introducing pT dependence to cuts results in lower S/B, better S/√(S+B) than old robust tight ID cuts • Needs better tuning • New suggested electron ID cuts mostly looser, dropped H/E cut • Better S/B & S/√(S+B) than old and new cuts, better efficiency than old cuts • PF isolation algorithm • Still needs work K. Grogg, UW-Madison

  18. BACK UP SLIDES K. Grogg, UW-Madison

  19. Low Acceptance for Electron ID at low & high pT Cuts are independent IDvariable < A K. Grogg, UW-Madison

  20. Low Acceptance for Electron ID at low & high pT Cuts are independent IDvariable < A+B pT K. Grogg, UW-Madison

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