Jets calibration using $t\bar{t}$ events


$t\bar{t}$ events with semileptonic decay of Ws.

$t\bar{t}$ $ \rightarrow $ $W^{+} b W^{-}\bar{b}$ $ \rightarrow $ $l \nu qq' b \bar{b}$




How to prepare the environment for the analysis
cmsrel CMSSW_3_3_4
cd CMSSW_3_3_4/src/
cvs co -d HiggsAnalysis/TTBarAnalysis UserCode/Bicocca/HiggsAnalysis/TTBarAnalysis
cvs co -d PhysicsTools/NtupleUtils UserCode/Bicocca/PhysicsTools/NtupleUtils

cd HiggsAnalysis/TTBarAnalysis
scramv1 b


Signal sample used

Feasibility study: MC analysis

Calibration algorithms

Main idea: invariant mass of the reconstructed jets $\sim$ M$_{W}$.

Jet correction coefficients are defined by

\[  p^{true} = k(\eta,p_{T}) p^{reco} \]
where $p^{reco}$ is the reconstructed momentum of the jet, $p^{true}$ is the correct momentum of the jet and k, the correction function, may depend on $p_{T}$ and $\eta$ of the jets. The purpose is to estimate the function
\[ k(\eta,p_{T}) \]
The function k has been "binned" in $\Delta\eta$ and $\Delta p_{T}$ rectangle in the $\eta, p_{T}$ plane. The width of these bins are determined by the number of events required by calibration algorithm (and then the number of events in a given integrated luminosity) and the accuracy on k that is required. It may be useful enable a dynamic binning of the function k according to the occupancy plot in the $\eta, p_{T}$ plane.

\[ k(i\eta,ip_{T}) \]

  • MiB : Minuit Bare minimization
  • kUpdate
  • RUL3 : Random Update L3
  • SL3: Squared L3
  • RUFit : Random Update Fit
  • SFit: Squared Fit

Jet from W identification in $t\bar{t}$ events

Background sample

$t\bar{t}$ events identification

Result: $t\bar{t}$ events and background

-- AndreaMassironi - 20-Jan-2010

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Topic revision: r2 - 2010-01-20 - AndreaMassironi
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