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TISB Pisa 12/10/01. HLT tau trigger with regional tracking. G. Bagliesi, S. Dutta, S. Gennai, G. Sguazzoni. Process studied. Low luminosity : Susy gg->(bb) A/H(200,500) -> (bb) tt -> 2 Jets+X Main background is QCD (50
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HLT tau trigger with regional tracking
G. Bagliesi, S. Dutta, S. Gennai, G. Sguazzoni
TISB Pisa 12/10/01
G. Bagliesi, S. Dutta, S. Gennai, C. Schmidt, G. Sguazzoni – bTau 250901 2
Process studied
Low luminosity: Susy gg->(bb) A/H(200,500) -> (bb) -> 2 Jets+X
Main background is QCD (50<PThat170)
Pixel “staged” scenario study: 3 layers + 2 disk: “standard” 2 layers + 1 disk: “staged” (preliminary
results!)
ORCA 4_5_4, CMSIM 120But we are reading the DB with ORCA_5_1_2No pixel read-out inefficiency
1233 scm102 L
G. Bagliesi, S. Dutta, S. Gennai, C. Schmidt, G. Sguazzoni – bTau 250901 3
Data samples
N prod After L1
Rate (kHz)
Weight
QCD 50-80 150000
8268 2x1.34
0.476
QCD 80-120 38501 13493 2x1.18
0.420
QCD 120-170 50000 25878 2x0.29
0.103
bbH(200) ->
5000 4465
bbH(500) ->
5000 4729
1233 scm102 L
G. Bagliesi, S. Dutta, S. Gennai, C. Schmidt, G. Sguazzoni – bTau 250901 48 June 2001 BTau MiniWorkshop - G.Bagliesi, S.Dutta, S.Gennai, G.Sguazzoni 3
Overview of the trigger chainOverview of the trigger chain
L1(Calorimeter based) A.Nikitenko et al. CMS NOTE 2000/055 A.Nikitenko talk in this workshop
HighLevelTrigger L2 (Calorimeter based)
see L1 refs.
L3Pxl (Pixel detector based) D.Kotlinski et al. CMS NOTE 2001/017 D.Kotlinski talk in this workshop
L3Tk (note in preparation): regional tracking based
G. Bagliesi, S. Dutta, S. Gennai, C. Schmidt, G. Sguazzoni – bTau 250901 5
No L2 applied on 1st jet: more flexibililityNo L2 applied on 1st jet: more flexibilility
H/A
1st jet
2nd jet
1st jet
trig
ger
chain
2n
d jet
trig
ger
chain
L3Tk (iso, #tk)
L1(iso)
.AND.L1
(iso)
L2(iso)
calo
calo
L3Tk(iso)p
ixel
tracker
calo
G. Bagliesi, S. Dutta, S. Gennai, C. Schmidt, G. Sguazzoni – bTau 250901 68 June 2001 BTau MiniWorkshop - G.Bagliesi, S.Dutta, S.Gennai, G.Sguazzoni 18
Tk isolation cutTk isolation cut
The leading track ofisolation cone should be inthe jet matching cone
All tracks within theisolation cone should beconcentrated in the signalcone
signal vertex
Similar to the L3Pxl
The regional tracking coneembeds all others cones
leading tracksignal cone
G. Bagliesi, S. Dutta, S. Gennai, C. Schmidt, G. Sguazzoni – bTau 250901 9
What is new?Look for a Pixel leading track in the jet matching cone (Rm=0.4, it was 0.1 before)If no pixel leading track is found, take the most probable signal vertex ~10% of good signal events recovered ~3% change in bkg: more probable to find a
leading track since more tracks are around…
Ptcut on leading track = 1 GeV (it was 3 GeV)
Reconstruct second tau jet (if any) pointing to the same signal vertex
G. Bagliesi, S. Dutta, S. Gennai, C. Schmidt, G. Sguazzoni – bTau 250901 10
Pt distribution from pythia
11
L2Tk jet tagging algorithm
“Good Track” definition PT>1 Gev |Z0-Zsignal|<0.2
Jet tau tagging: look for a fully reconstructed leading track with
PT>1 GeV (or calculate baricenter of tracks inside the cone) Apply isolation cut (already described)
Scan on Rs, Ri to find optimal parameters Rs=0.04, 0.06, 0.08, 0.1 Ri=0.4, 0.35, 0.3, 0.25, 0.2
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L2Tk on first and second jet
Rs
Ri
First jet only First and second jet
13
L2Calo + L3Tk isolation
With both Calo and Tk selection we can achieve the desired rejection
factor.
14
Summary PlotUsing:
• Rs = 0.04
• Ri = 0.3
And L2Calo on first jet we have:
• Bkg Rej = 10-3
• Sig Eff.
• MH500 = 45%
• MH200 = 35%
15
Staged pixel scenario
•2 barrel layers•1 forward disk•Comments:
•Track finder not optimized at seed level
•Preliminary!
10% signal efficiency degradation expected
Staged
Not staged
16
TauTkTagging.cc TauTkTagging(float eta, float phi, G3EventProxy
*ev)methods>: Vector<RecTrack> regionalTk()
Return a vector of reconstructed tracks inside jet cone and from the same primary vertex.
Bool isTau() Return true if the jet pass Tk isolation criteria.
Committed under bTauAnalysis/TauTaggingAlgorithms (works with ORCA_5_1_2)
17
Conclusions
Good signal efficiency ~40% (>30%) with ~103 background rejection factor is achievable using both jets for 500 Gev/c2 (200 Gev/c2) Higgs mass“Tau class” committed and working.To do: Improve speed: conditional track finding
implementation and evaluation Study the SimTracks to tune better the algorithm Tau Tagging: mass, vertex, I.P.
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