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Trigger Studies for HZ->bbvv

Alexandre Zabi, Jean-Francois Grivaz and Laurent Duflot (LAL-ORSAY). HIGGS GROUP December 6 th , 2002. Trigger Studies for HZ->bbvv. Outline. Look at the signal HZ->bbvv: Reproduce the cuts from Higgs-Susy workshop. Look at corresponding distributions. Trigger Studies:

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Trigger Studies for HZ->bbvv

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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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