Status of JLIP single top analysis.

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Status of JLIP single top analysis.
Benoit Clément, Denis Gelé IReS Strasbourg

• Overview
• Description of the analysis procedure
• Tagging and Taggability
• Discriminant variables
• Preliminary results (Data/MC comparison)
• Plans

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Analysis procedure
Dataset Full pass 2 dataset, processed with
Ipanema (JES 5.3) 360 pb-1 Same
preselection cuts and triggers than those used
for previous single top analyses.
B-tagging Use JLIP b-tagger in 4 modes 1
Tight tag gt 2 Tight tags the usual
ones 1 Tight, SuperLoose veto 1 Tight
and 1 SuperLoose Asymetric double tag
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Analysis procedure continued
Use MC for most of the backgrounds (tt,
dibosons) Use Higgs Wbb/Wjj sample with
normalization on data (Matrix Method) Qcd is
estimated on data, reversing lepton isolation
cuts -gt Nothing new
here
Final selection will be done using a Likelihood
discriminant method (1 for tt/signal and 1 for
Wjj/signal) Limits will be extracted on 2d
distribution of these LH.
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Taggability
New taggbility rate functions Estimated on very
loose preselected sample (1 loose lepton, 2 jets,
Met, DQ) Introduce PVz dependence
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Taggability RF closure plots (EM)
On preselected analysis sample (MM loose)
Real tggy TRFs
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Taggability RF closure plots (MU)
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Tagging and permutations
Advanced permuter code to manage complex tagging
patterns such as asymetric double tag
Consider several tagging state for a jet -
tag Tight - tag SuperLoose but not Tight
- not tag SuperLoose Use all permutations of
these 3 states that correspond to the desired
tagging pattern and compute the weight of each
permutation
!!! Procedure easy with JLIP as working point are
inclusive. This is not the case for SVT !!!
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Likelihood input variables
Tt / signal Likelihood s and t channel
Sphericity Min Dr between jets
Centrality Pt of 1st, 2nd and 3rd jet All
jet mass W tranverse MetPT Lepton t
channel only Q.?
Wjet / signal Likelihood s and t channel
Top mass (tagged jet) cos(j2,l) in top rest
frame Pt of 1st and 2nd jet All jet mass
W tranverse mas MetPT Lepton t channel
only Q.?
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Building the likelihood
We use MC samples to derive templates histograms
for the likelihood. Interpolatin is done by a
cubic spline on the templates.
Backgound templates for tt LH tt lepjet and tt
dilepton. Backgound templates for Wj LH Wjj,
Wbb, QCD.
Use PCA algorithm to approximate correlation
between variables (small improvement) see
arXivphysics/9805018, author Dean Karlen
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Preliminary results
tt / t-channel
tt / s-channel
Wjj / t-channel
Wjj / s-channel
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Top Mass distribution (EM)
DTag
STag
DTag Asym
STag Veto
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Top Mass distribution (MU)
DTag
STag
DTag Asym
STag Veto
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LH distribution (EM)
STag t-channel Wjj LH
STag t-channel Tt LH
DTag s-channel Wjj LH
DTag s-channel Tt LH
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LH distribution (MU)
STag t-channel Wjj LH
STag t-channel Tt LH
DTag s-channel Wjj LH
DTag s-channel Tt LH
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Conclusions and Plans
Most of the analysis is ready. First plots are
ready. Plots /work/kugelhopf-clued0/bclement/Si
ngleTop_Analysis_Summer05/ results
Still some issue on muon channel (Qcd ? Something
else) Problem with 2 working points tagging.
Whats missing - top_counts output should
be done quickly - JES scale errors need to
rerun everything with the shifts -gt next week
- computing limits !!!