First look at electron and jet distributions in W(?e ) jets and Z(?e e-) jets events

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First look at electron and jet distributions in
W(?e )jets and Z(?ee-)jets events
UK e/gamma Meeting, July 2005
Graham Kilvington Royal Holloway, University of
London
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Motivation

• W(? e nu) jets and Z(?ee-) jets will be
  important backgrounds to SUSY processes at the LHC

- missing ET, high pT jets and isolated leptons

• From the TDR

Using the parton shower model
Key
Z(?ll) n jets
W(?l nu) n jets
ttbar
QCD
Meff (GeV)
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Motivation

• However, using Matrix Element method of sample
  production suggests the background is larger than
  in TDR

Taken from S. Asai talk at Rome meeting
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Motivation

• Develop techniques to analyse these backgrounds
  from data

• Use Z(?ee) jets events to estimate the missing
  ET distribution for Z(?vv) events

• Use cross section and branching ratios of Z(?ee)
  jets events to normalise W(?ev) jets estimate

• Have a first look at the jet distributions of
  these events assumption is that they will be
  similar

- How true is this?
- Does the reconstruction introduce any effects?
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Method

• Using the 10.0.1 Rome production W(?ev) jets
  and Z(?ee) jets AODs, produced using Jimmy

• Using the SUSYPhys analysis program

• Cuts already in place in reconstruction code

• Electron pT gt 10 GeV
• Jet pT gt 10 GeV
• Eta lt 2.5

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Electron variables

• W

• Z

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Jet variables

• Z

• W

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N jets for different e- reco

• W

Red Truth
Black Reco
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N jets for different e- reco

• Z

Red Truth
Black Reco
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Individual jet pT

• W

0 Reco e-
Highest pT jet
2nd highest pT jet
3rd highest pT jet
4th highest pT jet
5th highest pT jet
6th highest pT jet
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Individual jet pT

• W

1 Reco e-
Highest pT jet
2nd highest pT jet
4th highest pT jet
3rd highest pT jet
5th highest pT jet
6th highest pT jet
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Individual jet pT

• Z

0 Reco e-
Highest pT jet
2nd highest pT jet
4th highest pT jet
3rd highest pT jet
5th highest pT jet
6th highest pT jet
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Individual jet pT

• Z

1 Reco e-
Highest pT jet
2nd highest pT jet
4th highest pT jet
3rd highest pT jet
5th highest pT jet
6th highest pT jet
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Individual jet pT

• Z

2 Reco e-
Highest pT jet
2nd highest pT jet
4th highest pT jet
3rd highest pT jet
5th highest pT jet
6th highest pT jet
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Reco-Truth matching

• W

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Reco-Truth matching

• Z

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Plans from here

• See how using different jet algorithms affects
  jet reconstruction and the results shown above

• Develop techniques to estimate SUSY backgrounds
  from data samples

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