W Cross Section measurement at CDF RunII University Of Athens and - - PowerPoint PPT Presentation

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W Cross Section measurement at CDF RunII University Of Athens and - - PowerPoint PPT Presentation

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W Cross Section measurement at CDF RunII University Of Athens and INFN-Sezione di Pisa University Of Athens and INFN-Sezione di Pisa HEP2006 Ioannina 13-16 April HEP2006 Ioannina 13-16 April Athanasios Staveris-Polykalas Athanasios

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W Cross Section measurement at CDF RunII

University Of Athens and INFN-Sezione di Pisa University Of Athens and INFN-Sezione di Pisa HEP2006 Ioannina 13-16 April HEP2006 Ioannina 13-16 April Athanasios Staveris-Polykalas Athanasios Staveris-Polykalas

e+

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Outline

Athanasios Staveris-Polykalas

Why the W cross section Why the W cross section W cross section at CDF W cross section at CDF W boson in Forward region W boson in Forward region Strategy of analysis Strategy of analysis Results Results Conclusions Conclusions

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3 Athanasios Staveris-Polykalas

Why W cross section

Precise electroweak measurements

  • > Constrain Standard Model (or)

Suggest Physics Beyond Standard Model

W signal is well established

  • > Base of detector performance studies

Cross section measurement

  • > Ensure good understanding of
  • > Common cross check for other analyses

e

NEW DATA AVAILABLE!! NEW DATA AVAILABLE!!

  • > ~300 pb
  • > ~300 pb-1
  • 1 of additional data collected
  • f additional data collected

2003-2004 2003-2004

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W cross section at CDF

Tevatron -> W hadronic decay is overwhelmed by QCD

  • > W boson is identified by the leptonic decay (in our case

electron neutrino)

Br W e= N Data - N Background A L dt N Data N Background A

  • L dt

= # of observed events = # of expected background = Geometric and kinematic Acceptance (from MC) = efficiency (trigger, reconstruction, ID) = integrated Luminosity

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W boson in Forward region of CDF detector

Central drift chamber Central drift chamber Central drift chamber Central drift chamber Silicon Detector Silicon Detector Plug Detector Plug Detector Extended electron ID to forward region Extended electron ID to forward region

  • f detector->
  • f detector->1.2||2.8

Use of combined information from Use of combined information from forward EM calorimeters and forward EM calorimeters and extended tracking system (ISL) extended tracking system (ISL) Increases statistics for other physics Increases statistics for other physics analyses for the given luminosity analyses for the given luminosity i.e. top physics, W F/B charge i.e. top physics, W F/B charge asymmetry asymmetry

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Strategy of analysis

Event selection: Event selection:

  • Trigger (Missing Et +

Trigger (Missing Et + Plug EM object) Plug EM object)

  • Electron ID

Electron ID (Had/Em<0.05 && IsoRel<0.1) (Had/Em<0.05 && IsoRel<0.1)

  • 1.2||2.8

ET20GeV MET25GeV

Calorimetric Calorimetric Cuts Cuts

  • Track matching

E/p< 2

|X| ,|Y |3cm

Track Cuts Track Cuts

We end up with 48144 48144 candidate events

Acceptance from MC Acceptance from MC Efficiencies from Z->ee data Efficiencies from Z->ee data and MC and MC Background from data and Background from data and MC MC

  • Largest systematic contribution

Largest systematic contribution from Acceptance ~2% (PDFs) from Acceptance ~2% (PDFs)

  • Total background contamination

Total background contamination ~4.5% ~4.5%

  • Acceptance x Efficiency of signal

Acceptance x Efficiency of signal selection ~7 % selection ~7 %

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RESULTS

N Data=48144 Acc=0.25550.0002stat-0.0039

0.0048syst

Total=0.07320.0011stat- 0.0019

0.0021syst

N BckQCD=87759stat438syst N BckZ ee=2333stat N BckW =107312stat

Ldt=22313syst

Numerator Numerator Denominator Denominator Br W e= N Data - N Background A L dt

Br W e=281513stat-89

94syst169lum pb

Forward CDF W cross section measurement with 223 pb Forward CDF W cross section measurement with 223 pb-1

  • 1

Theoretical Prediction: Theoretical Prediction: NNLO (Stirling, van NNLO (Stirling, van Neerven) Neerven)

Central CDF W cross section measurement with 72 pb Central CDF W cross section measurement with 72 pb-1

  • 1

Br W e=278014stat60syst167lum pb Br W eTh=268754 pb

P u b l i s h e d C D F N u m b e r s P u b l i s h e d C D F N u m b e r s

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10

  • 1

1 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5

Ecm (TeV) σ × Br (nb)

σ×Br(W→lν) σ×Br(Z→l+l-)

CDF II (e,1.2<|η|<2.8),223 pb-1 CDF II (e+µ),72pb-1 CDF II Z(µ), 337pb-1 CDF II Z(τ), 349pb-1 CDF I (e) DO I (e) D0 II (e) D0 II (µ) CDF (630) UA1 (µ) UA2 (e) NNLO theory curves:

Martin, Roberts, Stirling, Thorne

Athanasios Staveris-Polykalas

Our contribution to physics Our contribution to physics http://www-cdf.fnal.gov/physics/ewk/2006/plugw/ http://www-cdf.fnal.gov/physics/ewk/2006/plugw/

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Conclusions

Our measurement consistent with central results and theory

Our measurement consistent with central results and theory

  • Better understanding of plug region of CDF detector

Better understanding of plug region of CDF detector

  • More data can be used for other analyses:

More data can be used for other analyses: (Top physics and W Forward-Backward charge (Top physics and W Forward-Backward charge asymmetry) asymmetry)

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From now on Backup

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Zee control sample

Central tight electron +

Control sample Z->ee (CP)

MC zewk6d for Z->ee (~1.9M) data zewk0d for Z->ee (223pb-1)

In efficiency and trigger study we apply invariant mass window 80-100 GeV Control sample used for:

Efficiency evaluation L2,L3_PEM20 trigger study Evaluating Scale&Smear

parameters -> tuning parameter applied on energy

Plug leg :

Loose plug electron

(denom for eff study) 1.2<|eta|<2.8 Et >20GeV Had/Em<0.125

ID selection

Had/Em<0.05 IsoRel <0.1

Track matching

3D Track Matched (pt>1GeV, ∆ X,Y < 3cm)

E/P<2

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Efficiency:

L1_EM8 =99.9988 ± 0.0007(stat) % L1&L3_MET15 = 99.42 ± 0.1 L2_PEM20 = 95.99 ± 0.37(stat) % L3_PEM20 = 99.61 ± 0.1(stat) %

EffTOT = EffL1_MET15 & L3_MET15 x EffL2_PEM20 x EffL3_PEM20|L2_PEM20 EffTOT = 95.06 ± 0.009 (stat) %

Trigger summary

+0.0009(syst)

  • 0.0061(syst)

+0.87(syst)

  • 1.05(syst)

+0.009(syst)

  • 0.015(syst)

+0.31(syst)

  • 1.12(syst)
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Requirement

  • N. Of events

East West 724062

  • 706735

373104 393640 689504 338205 360090 251692 125681 126154 79800 40677 39139 Matching track 74091 37826 36267 71861 36797 35066 E/p <2 48144 24591 23553 MET_PEM trigger fired

1.2||2.8 ET20GeV IsoRel0.1, Had /Em0.05 MET25 GeV

|TrkZ 0|60cm

# events per cut

Athanasios Staveris-Polykalas

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Systematics

Source

  • Syst. Uncertainty(%)
  • Syst. Uncertainty(%)

+/-0.232 +/-0.232 +/-0.043 +/-0.043 +/-0.031 +/-0.031 +/-0.35 +/-0.35 +/-0.713 +/-0.713 +2,55-1,7 (CTEQ) +1.70-1.29(CTEQ+PRD) +/-0.049 +/-0.049 +2,68-1,89 (CTEQ) +1.89-1.54 (CTEQ+PRD)

plug E T

e scale

ET

e resolution

PT

  • U

Material PDF' s PVZ study Total

Athanasios Staveris-Polykalas

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DET

η

  • 2
  • 1

1 2 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

  • Track. Eff.

Combined Inside Out Outside In SiSa

Eff vs track algo

Athanasios Staveris-Polykalas