Light h 0 decay in SUSY cascade Jet Reconstruction & B tagging
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Transcript of Light h 0 decay in SUSY cascade Jet Reconstruction & B tagging
Alain Romeyer - March 2005 1
Light h0 decay in SUSY cascade
Jet Reconstruction & B tagging
Introduction
First use of DST
Jet reconstruction and calibration issues
B tagging
Conclusion
Filip Moortgat (CERN)Alain Romeyer (Mons - Belgium)
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Introduction
Benchmark point LM5Tan = 10AO = 0µ > 0M1/2 = 360 GeVM0 = 230 GeV
MSUGRA 5 parameters : m0, m1/2, A, tan , sign(µ)
S. Abdullin – L. Pape Update II of the new MSUGRA test points proposal
0 02 1
0 0
g
q
χ χ
H h
m ~ 860GeV
m ~ 800 GeV
m ~ 273 GeV m ~ 142 GeV
m ~ 570 GeV m ~ 116 GeV
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Signatures
p
p
01χ
0h
q
gor
q
02χ
q
b
b
LSPMET
B tagging
85 %
72 %
~35 %
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Signatures…
Main background expected to come from SUSY itself!!! (sbottom…)
100 000 evt production of all SUSY channels (20% of them contain our signal)
SM background expected small (Z+jets, top…) rejected by high jet multiplicity and important MET was not our priority (analysis has just started CRAB & LCG)
Reconstruction strategy focus on jet reconstruction, b tagging and MET
Access info from DST using ORCA_8_7_2 test of official Jet Calibration (GammaJet) Try different Track Counting significance threshold
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DST Jet calibrationOnly b jets coming from h0 decay (mh = 116 GeV)
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Jet E resolutionOnly b jets coming from h0 decay (mh = 116 GeV)
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Minv (Signal + SUSY bkg)
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Comparison with private calib.
Only b jets coming from h0 decay (mh = 116 GeV)
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Jet E resolutionOnly b jets coming from h0 decay (mh = 116 GeV)
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IC with 0.7 cone size
No calibration for 0.7 cone 0.5 cone calibration used !!!
Only b jets coming from h0 decay (mh = 116 GeV)
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BtaggingTrack Counting Algo. (only b tagged jets)
Tag jet if 2 tracks are found above a given Significance threshold
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B tagging eff/mistag
54.151.4
4.9
16.6
47.845.1
3.5
12.3
42.840.2
2.9
9.7
0.0
10.0
20.0
30.0
40.0
50.0
60.0
b b from h uds c
Eff
icie
ncy
/ I
nef
fici
ency (
%)
S > 3
S > 4
S > 5
IC cone = 0.5
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Impact on Minv (Signal)Only b jets coming from h0 decay (mh = 116 GeV)
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Minv (Signal + SUSY bkg)
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Conclusion Jet calibration on DST for 0.5 cone and IC algo
is working
Jet reconstruction performance with other cone size cannot be done with DST info (no calibration)
Hardest cut for B tagging Track Counting does not improve the S/B ratio
Solution : try to reconstruct the jet charge
SM bkg analysis started (on LCG using CRAB) in particular for tt inclusive
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Conclusion…