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Trigger Studies for Higgs Decay HZ -> bbvv: Efficiency Analysis and Optimization

This study investigates the trigger conditions necessary for the Higgs to bbvv decay channel using data from the Higgs group. Key aspects include reproducing previous cuts from the Higgs-SUSY workshop, analyzing distributions, and conducting comprehensive efficiency studies across trigger levels (Level 1, Level 2, and Level 3). The performance metrics reveal an overall efficiency of 85% with various discriminating variables identified for optimizing cuts. The results provide crucial insights into enhancing trigger algorithms to support future Higgs analyses.

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Trigger Studies for Higgs Decay HZ -> bbvv: Efficiency Analysis and Optimization

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  1. Alexandre Zabi, Jean-Francois Grivaz and Laurent Duflot (LAL-ORSAY). HIGGS GROUP December 6th, 2002 Trigger Studies for HZ->bbvv

  2. Outline • Look at the signal HZ->bbvv: • Reproduce the cuts from Higgs-Susy workshop. • Look at corresponding distributions. • Trigger Studies: • Rate and Efficiency studies at all Levels. • Choose a Trigger condition at Level1 (CJT(x,x)?). • Look for Discriminating Variables (signal/bkg) at L2 and L3 • Optimized cuts on Level2 and Level3 variables in order to get a factor of 10 of rejection for each Level. • Overall efficiency.

  3. The Signal: HZ->bbvv (MH=115) Higgs Group p10 MC files: Data Set: higgswg_zh_nunu_bb_m115_mixture-v002 (8K events). Reco Version: p10.08.01. Jet Energy Scale correction (Jets and MEt): version 01.01.02. Jet certified cuts using JCCB jets. Reproduce Cuts from Higgs-Susy Workshop 1998: • 2 bjets tagged with: - one with Pt > 20 GeV and lηl < 2 - one with Pt > 15 GeV and |η| < 2 • MEt > 35GeV • Angle between MEt and closest jet δΦ> 0.5 (28 degrees)

  4. Find b quarks in MC sample. b quark parent  Higgs? Is there a certified JCCB jet with Pt > 15GeV and ΔR < 0.5 ? (ΔR wrt bquark direction) bjet Reconstruction Njets(certified,Pt>15GeV) = 18600  Nbjets = 14139.

  5. Jet Pt

  6. MEt

  7. Analysis Cuts Summary

  8. LEVEL 1 MC Sample = 8000 Events.  TRIGSIM (p12.05.00) on Sample. Signal Sample = 2974 Events. Signal Sample = MC sample after Analysis cuts. CJT(3,5) (current multijet standard) CJT(3,5)  2387 Events CJT(2,5) CJT(2,5)  2792 Events Efficiency = 80% TOO LOW! Rate = 100 Hz Efficiency = 94% Rate = 440 Hz TOO HIGH! Rate from Trigger List 8.20 spread sheet rescaled for Luminosity = 40E30 cm-2 s-1

  9. To determine CJT(2,5)CJT(3,3) rate:  We need an unbiased CJT(2,5)data sample.  We use JT_25TT_NG MarkAndPass events (Trigger List 8.20). JT_25TT_NG: CJT(2,5) at Level1. No conditions at Level2. Data Sample: List of Runs using the trigger List 8.20. Pick_events to retrieve those events.  1000 Events also used as background sample for Level 2 and Level 3 Trigger studies. LEVEL 1 We could use CJT(2,5)CJT(3,3)

  10. LEVEL 1 Signal Sample  2974 Events CJT(2,5)CJT(3,3)  2751 Events Efficiency = 93% Rate = 300 Hz REASONABLE!? Rate for Luminosity = 40E30 • Rate reasonable considering: • Factor of 100 L2/L3 rejection. • L1 bandwidth will increase. • We expect CJT(n,3) to be less noisy.

  11. LEVEL 2 Level 2 jets:L2CalJet. • We consider 5x5TT jets, No explicit threshold cuts, Require 2 Jets in the Event. L2 NJET background signal  Efficiency wrt Level 1 = 98%

  12. LEVEL 2 Pt LEADING JET background signal

  13. LEVEL 2 Pt 2nd LEADING JET background signal

  14. LEVEL 2 HT = |Pt(jets)| background signal

  15. LEVEL 2 MHT = | Pt(jets)|  An algorithm should be implemented very soon (Adam Yurkewick) background signal

  16. LEVEL 2  = Angle between leading jets in transverse plan. L2CalJet_L2JPhi is an integer[1,160]   [1,80] background signal

  17. LEVEL 2 MHT and   Most discriminating variables -   80 -   75 -   70 -   65 -   60 Mht > 0 to 40 GeV

  18. LEVEL 2  Try other combinations of variables

  19. LEVEL 3 Level 3 jets:SCJET_9. • Simple Cone Jet Algorithm, Jet Pt > 9GeV, Require 2 Level3 Jets. L3 NJET background signal  Efficiency wrt Level 2 = 97%

  20. LEVEL 3 Pt LEADING JET background signal

  21. LEVEL 3 Pt 2nd LEADING JET background signal

  22. LEVEL 3 HT = |Pt(jets)| background signal

  23. LEVEL 3 MHT = | Pt(jets)| background signal

  24. LEVEL 3  = Angle between leading jets in transverse plan. background signal

  25. LEVEL 3 MHT Most discriminating variables (No obvious gain with two variables combined) MHt > 0 to 30 GeV • For MHt > 18 GeV • Efficiency(wrt L2) = 97% • Rate = 3 Hz

  26. Summary OVERALL L1+L2+L3 EFICIENCY  85%

  27. Conclusion • Acceptable Scheme using pure Calorimeter Trigger • Overall L1/L2/L3 efficiency = 85% • Level 2 MHt certified algorithm underway (Adam Yurkewicz). • MEt at Level 3 could improve efficiency (to be compared with MHt).

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