feasibility of detecting leptoquarks with the cdf detector althea moorhead mentor: darin acosta
TRANSCRIPT
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Feasibility of Detecting Leptoquarks With the CDF Detector
Althea MoorheadMentor: 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 .
Interested in region of small .
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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
W+jets 67
Z 36
Z+jets 20
Top quark 7
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Sensitivity vs. Missing Energy
The statistical significance:
Statistical significance not very dependent on the missing energy
SS B
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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 CutsMissing Transverse Energy 40 GeV
Number of Jets = 2 or 3 (Energy 35 GeV)No other jets with energy > 7 GeV
0.1 Jet em fraction 0.9(MET, j) > 45
(MET, j1) < 165
45 < (j1, j2) < 165Electron Veto
Jet
Jet
Missing Energy
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Cross Section Upper Limits Find upper limits
on leptoquark events, then:
N L
N
LM M
obs
ULobs UL
LL UL
FHG
IKJ
FHG
IKJ
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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