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Update of trigger study for GMSB photons

Update of trigger study for GMSB photons. Shilei Zang University of Colorado, Boulder. GMSB Meeting, 14th Dec. 2007. Outline. Signal efficiency Background samples processed Efficiency vs. Rates Log(eff)/log(b) vs. Cuts Preliminary results Backup slides: Eff. vs. Cuts; Rates vs. Cuts.

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Update of trigger study for GMSB photons

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  1. Update of trigger study for GMSB photons ShileiZang University of Colorado, Boulder GMSB Meeting, 14th Dec. 2007

  2. Outline Signal efficiency Background samples processed Efficiency vs. Rates Log(eff)/log(b) vs. Cuts Preliminary results Backup slides: Eff. vs. Cuts; Rates vs. Cuts.

  3. GMSB sample and Background samples • Bob Hirosky’s GMSB samples at CMSSW_164 are used to estimate signal efficiency. • I used 10000 GMSB events: 900 GM1b, 800 GM1c, 1800 GM1d, 5900 GM1e, 600 GM1g. • PreCSA07 (or CSA07) samples are used to estimate the background rates, which includes: • Photon jets (all pt bin) • QCD jets (all pt bin) • Wenu, Zee, will be included in rate calculation soon. (since CSA07 Wenu sample is available just in December.)

  4. HLT paths for photons • L1Match: Reconstructed super-cluster in the ECAL is required to match L1 energy deposit in some eta and phi windows. • Et : Et of super-cluster in the ECAL is required to exceed a threshold. • IEcal: ECAL isolation, total Et of all clusters with ΔR<0.3 around the photon candidate, excluding those belonging to the super-cluster itself. • IHcal: HCAL isolation, total Et of hadron calorimeter towers with ΔR<0.3 around the photon candidate. • Itrack: Track isolation, number of tracks with Pt>1.5GeV inside a cone ΔR<0.3 of photon candidate.

  5. Signal Efficiency (GMSB photons)

  6. How many events in each background samples do we need to process in the rate calculation • Suppose the i-th sample has cross section σi; with a definite integrated luminosity there will be Nievents of i-th sample ; with some cuts we will select ki events; efficiency of cuts on the i-th sample is εi= ki/ Ni. • Both ki and Niare Poisson distribution, and independent, so error of εi is σ(εi)=Sqrt(εi(1+ εi)/ Ni). • With instant luminosity L, rate of i-th sample is Lσiεi, with an error of Lσiσ(εi). • To keep a small error of total rate and reduce the number of events to process, we require Lσiσ(εi)= Lσjσ(εj), so • Ni /Nj = (σi / σj)2[εi(1+ εi)]/[εj(1+ εj)]. • Process the i-th sample with small number of events (finally needs to select ~100 events, so the relative error of εi is ~10%) ; roughly determine the efficiency εiwith all default HLT paths will use. Then get the ratio of Ni /Nj.

  7. Background samples processed (1)

  8. Background samples processed (2)

  9. Background samples processed (3)

  10. Efficiency vs. Rates (Single Photon) • Final Rate is about : • 9.4+-0.5, for single photon path. • HLT study group resut (CMSSW131): • 8.4+-0.7.

  11. Efficiency vs. Rates (Relaxed Single Photon) • Final Rate is about : • 3.0+-0.2, for relaxed single photon path. • HLT study group resut (CMSSW131): • 2.8+-0.2.

  12. Efficiency vs. Rates (Double Photon) • Final Rate is about : • 0.29+-0.07, for relaxed single photon path. • HLT study group resut (CMSSW131): • 0.6+-0.4.

  13. Efficiency vs. Rates (Relaxed Double Photon) • Final Rate is about : • 1.81+-0.15, for relaxed single photon path. • HLT study group resut (CMSSW131): • 1.8+-0.5.

  14. Log(eff)/log(b) vs. Cuts (Single Photon)

  15. Log(eff)/log(b) vs. Cuts (Relaxed Single Photon)

  16. Log(eff)/log(b) vs. Cuts (Double Photon)

  17. Log(eff)/log(b) vs. Cuts (Relaxed Double Photon)

  18. Preliminary Conclusion • Rates are comparable with previous CMSSW_131 results given by HLT study group. The rates here have small errors. • From the figures, we suggest to relax the isolation cuts, especially Ecal isolation and Track isolation. We will give the suggested thresholds later. • Wenu and Zee samples will be included in rates calculation soon. Some other samples will be processed with more events.

  19. Efficiency vs. Cuts (Single Photon)

  20. Efficiency vs. Cuts (Relaxed Single Photon)

  21. Efficiency vs. Cuts (Double Photon)

  22. Efficiency vs. Cuts (Relaxed Double Photon)

  23. Rates vs. Cuts (Single Photon)

  24. Rates vs. Cuts (Relaxed Single Photon)

  25. Rates vs. Cuts (Double Photon)

  26. Rates vs. Cuts (Relaxed Double Photon)

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