Btag Certification Macros

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Btag Certification Macros

• G. Watts

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Certification is a lot of work

• Many
• Plots, Scripts, Cross checks
• Calculation of Eff and fake
• Calculation of systematic errors
• Calculation of TRFs
• Major pieces are common across taggers
• Write a common set of scripts

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2 Packages
btags_cert
btags_cert_macros

• Abstract Interface To All taggers (BTag)
• Implementation of all Certified Taggers
• At certified operating points
• Also designed to be used by analyzer
• Will return info for combination taggers

• Scripts and programs to generate plots and
  perform calculations.
• Generate TRFs, eff plots, etc.

Based on d0root
(TMB, TMBTree, top_tree)
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btags_cert Status

• JLIP, CSIP, SVT Tagging Algorithms
• LOOSE, MEDIUM, and TIGHT operating points
  implemented.
• JLIPs track parameter error present until last
  release
• TRFs for above
• SVT completely implemented
• Flavor dependent
• Automatic determination of jet flavor
• Muon correctly handled
• Define your own TRF
• JLIP, CSIP
• Infrastructure there, but not completely
  implemented yet.
• About 2 hours of work left.
• Documentation
• Uhm, no, not really.

Has been used in several analyses
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btags_cert_macros Status
Under Active Development
Start with some definitions

• All groups should be using the same definitions!
• Can cause biases if not defined properly when TRF
  is generated and used!

A Jet has a Muon in it if
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DR (m, jet axis) lt 0.5
m is pTgt1.0, medium
Jet Energy is JES corrected, but with out the
muon correction!
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This must also be used when the TRF lookup is
done.
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Definitions Cont
Jet Flavor Based on meson, not quark
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b-jet DR(b-meson, jet axis) lt 0.5
c-jet DR(c-meson, jet axis) lt 0.5 not b-jet
light-jet not b-jet not c-jet
Single python script manages all steps
Output is HTML
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Runs MC Samples
Tag Efficiency
B-quark, All Jets, positive tags (JLIP TIGHT)
ETA

• Plots
• Raw MC Sample Pass Rates

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MC Comparisons
B-quark, All Jets, positive tags (JLIP TIGHT)
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Building MC TRFs
Draw from Zbb, Zbbmu, Zcc, etc. samples
MC TRF is a Matrix of 2x3 2d-funtions
Matrix is by jet flavor (light, charm,
bottom) and by muon content (with muon, without)
2D function is pT and h.
Makes eff vs fake for any TRF
Start of code to break down systematic error
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Calculating The Fake Rate
Uses EMQCD negative tag rate.
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eN
1
el
SPN
RlRbSbl
el
1
Light Quark Tagging Efficency
eN
Measured Negative Tag Rate
pT
SPN
Ratio of light neg tags over positive
Rl
Fraction of light quark jets (1-Rb)
Rb
Fraction of b quark jets (3 w/20 error)
Sbl
Ratio of neg b tags over light
QCD MC is used for calculating the ratios
currently
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Systematic Error Breakdown
Largest Error By Far
Neg b tag error
Using QCD to find neg tag rate for bs so
statistics are awful right now.