Trigger Studies for HZ->bbvv

1
Trigger Studies for HZ-gtbbvv

• Alexandre Zabi, Jean-Francois Grivaz and Laurent
  Duflot (LAL-ORSAY).
• HIGGS GROUP
• December 6th, 2002

2
Outline

• Look at the signal HZ-gtbbvv
• 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-gtbbvv (MH115)

• 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 gt 20 GeV and l?l lt 2 - one with Pt
  gt 15 GeV and ? lt 2
• MEt gt 35GeV
• Angle between MEt and closest jet dF gt 0.5 (28
  degrees)

4
bjet Reconstruction

1. Find b quarks in MC sample.
2. b quark parent ? Higgs?
3. Is there a certified JCCB jet with Pt gt
   15GeV and ?R lt 0.5 ? (?R wrt bquark
   direction)

Njets(certified,Ptgt15GeV) 18600 ? Nbjets
14139.
5
Jet Pt
6
MEt
7
Analysis Cuts Summary
MC SAMPLE 8000 Events
2 bjets with ? lt 2 Leading Pt gt 20GeV 2nd Leading Pt gt 15GeV 5658 Events
Met gt 35 GeV 3796 Events
??(Met-closest jet) gt 0.5 2974 Events
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 94 Rate 440 Hz TOO HIGH!
Efficiency 80 TOO LOW! Rate 100 Hz
Rate from Trigger List 8.20 spread sheet rescaled
for Luminosity 40E30 cm-2 s-1
9
LEVEL 1
We could use CJT(2,5)CJT(3,3)

• 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.

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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 integer1,160 ? ??
1,80
signal
background
17
LEVEL 2
MHT and ?? ? Most discriminating variables
- ?? ? 80 - ?? ? 75 - ?? ? 70 - ?? ? 65 - ?? ?
60 Mht gt 0 to 40 GeV
18
LEVEL 2
? Try other combinations of variables
Variables Optimized cuts for Rate 30Hz Efficiency
?? / MHT ?? ? 75, MHt gt 25 GeV 94
?? / HT ?? ? 65, HT gt 60 GeV 78
?? / Pt (lead Jet) ?? ? 70, Pt gt29 GeV 90
MHT/Pt(lead jet) MHT gt 20GeV Pt gt 30GeV 91
MHT/HT MHT gt 20GeV HT gt 60GeV 85
HT/Pt(leadJet) HT gt40 GeV Pt gt39 GeV 81
19
LEVEL 3

• Level 3 jets SCJET_9.
• Simple Cone Jet Algorithm, Jet Pt gt 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)
signal
background
24
LEVEL 3
?? Angle between leading jets in transverse
plan.
signal
background
25
LEVEL 3
MHT ? Most discriminating variables (No obvious
gain with two variables combined)
MHt gt 0 to 30 GeV

• For MHt gt 18 GeV
• Efficiency(wrt L2) 97
• Rate 3 Hz

26
Summary
LEVEL Condition Rate Efficiency
LEVEL 1 CJT(2,5)CJT(3,3) 300Hz 93
LEVEL 2 ?? ? 75, MHt gt 25GeV 30Hz 94 Wrt L1
LEVEL 3 MHt gt 18GeV 3Hz 97 Wrt L2
OVERALL L1L2L3 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).