Feasibility of Detecting Leptoquarks With the CDF Detector

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Feasibility of Detecting Leptoquarks With the CDF
Detector

• Althea Moorhead
• Mentor Darin Acosta

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Outline

• Background What is a leptoquark?
• Leptoquark production and previous work
• Results Calculations
• Conclusions

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The Standard Model

• Quarks, leptons, and gauge particles (force
  carriers)
• Arranged into three generations
• Why is there a correlation between quarks and
  leptons?

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Leptoquarks

• Predicted by grand unified theories,
  supersymmetry, and string theory
• Would be bosons
• Would have characteristics of both quarks and
  leptons

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Leptoquark Production

• Gauge Coupling
• Mediated by gauge bosons
• Yukawa Coupling
• Direct fusion of a lepton and a quark

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The Tevatron

• Proton-antiproton collider
• Energy of 1 TeV (most energetic in the world)
• Run 1 100 pb-1
• Run 2 2000 pb-1

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The CDF Detector

• Tracking chamber maps the trajectories of charged
  particles
• Calorimeters measure particle energies

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Background Current Leptoquark Limits

• Leptoquarks decay into a lepton and a quark.
• Probability of that lepton being charged is the
  branching ratio b.
• Interested in region of small b.

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Procedure

• Simulate leptoquark and background events
• PYTHIA event simulation
• cdfSim detector simulation
• Production event reconstruction
• Stntuple event analysis
• Use cuts to differentiate between signal and
  background

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Missing Transverse Energy

• Leptoquark Background

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Table of Expected Events
Type Nobs
Leptoquark 100 GeV 58
150 GeV 14
Background QCD 195
W 100
Wjets 67
Z 36
Zjets 20
Top quark 7
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Sensitivity vs. Missing Energy

• The statistical significance
• Statistical significance not very dependent on
  the missing energy

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Sensitivity vs. Min. Jet Energy

• Statistical significance is dependent on the
  minimum jet energy
• Peak at about 35 GeV

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Other Cuts
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Cross Section Upper Limits

• Find upper limits on leptoquark events, then

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Projected New Limits
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Mass Limit vs. Luminosity
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Conclusions

• Results consistent with previous work
• Experimental data will change these results
  somewhat
• Could be improved with heavy flavor tagging