Recent Results in High pT Physics from CDF

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Recent Results in High pT Physics from CDF

• Gregory Veramendi
• UC Berkeley / LBNL
• (For the CDF Collaboration)

Introduction Data taking and CDF II upgrade
Electroweak Results Top Results Searches for
new Physics
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CDF data taking

• Running stably since Feb. 02
• Silicon sensitive to beam conditions
• gt150 pb-1 to tape
• 5-8 pb-1/week
• 82 efficiency
• 53-91 pb-1 used in current winter analyses

Approved for analysis
Commissioning
July 2001
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CDF Run II Upgrade

• Improved Si coverage
• ? lt 2
• 8 layers
• Central Drift Chamber
• 96 layers
• Time of Flight
• Expanded ? coverage
• Forward Calorimeter
• Trigger
• COT tracks at L1
• Silicon tracks at L2

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Electroweak Program

• Baseline Measurements
• W/Z cross sections
• Ratio of W/Z cross section
• Lepton Universality
• Forward-Backward Asymmetry
• Improve EWK parameters
• W Charge Asymmetry
• Constrains on PDFs
• Diboson Production
• Look for Anomalous couplings
• W Mass Measurement
• Dominated by Systematics

W?e?
Z???
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?B(W--gtl?l)
W--gt??

• Clean Signature
• Isolated lepton
• Missing ET
• High ? S/B
• 72 pb-1

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?B(Z--gtll)

• Require two isolated leptons
• Negligible backgrounds
• 72 pb-1
• Essential for Detector Calibrations
• Energy scale and resolution
• ID efficiency

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W and Z cross sections
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R and GW
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W??? and Lepton Universality

• Clean W??? decays
• Baseline for analyses using ?s

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AFB using Dielectrons

• Forward-Backward Asymmetry
• Exploits forward coverage of electrons
• ?lt3
• Direct probe of ?,Z couplings
• Sensitive to interference from new physics
• High mass reach is unique to Tevatron
• Results consistent with SM

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W?e? Charge Asymmetry

• Al constrains PDFs
• Charge ID and polar coverage essential
• Uses new Calorimeter seeded Silicon tracking
• Consistent tracking ?lt2
• Improvement on Run I
• Blind Analysis
• Results Summer

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Diboson CouplingsW?

• Signature
• One high pT lepton
• One photon (?R(?-l)gt0.7)
• ET
• Results consistent with SM
• SM ?B(W?--gtl??) 18.7 1.3 pb

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Diboson CouplingsZ?

• Signature
• Two high pT leptons
• One photon (?R(?-l)gt0.7)
• Results consistent with SM
• SM ?B(Z?--gtll?) 5.4 0.4 pb

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DibosonWW

• Search for W W production
• Dilepton ET search
• Consistent with SM
• Wait for more statistics
• Precursor to SM Higgs Search

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Top Program

• Establish Baseline Measurements from Run I
• Top cross section
• Precision test of QCD
• Probe for non-SM Production
• Top Mass
• Preliminary Result
• Getting machinery warmed up!
• Many precision tests of top to come with more data

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Production and Decay of Top

• Top decays as a free quark
• ?top 4x10-25s
• BR(t-gtWb) 100
• 3 classes of signals
• Dilepton
• 2 high-pT leptons, 2 b jets, ET
• BR 1/9 (e,? 5)
• Lepton Jets
• 1 high-pT lepton, 4 jets (2 bs), ET
• BR 4/9 (e,? 30)
• All-hadronic
• 6 jets (2 bs)

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/
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Dilepton Cross Section

• Signature
• Two high pT Isolated leptons
• Veto Z, cosmic, conversion
• ??(ET,l/j)gt20o, or ETgt50 GeV
• ET gt 25
• Two jets with ETgt10 GeV
• Total transverse energy gt 200 GeV
• Expect S/B 9, S2.5
• Find 5 candidate events in 72 pb-1
• Expect 0.3 0.12 background events

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/
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?tt13.2 5.0stat 1.5syspb
NLO?tt(?s1.96 TeV)6.700.71-0.88 pb
(hep-ph/0303085(ML Mangano et al))
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Lepton jet Cross Section

• Signature
• One high pT Isolated lepton
• Veto Z, cosmic, conversion
• ET gt 20 GeV
• 3 or more jets with ETgt15 GeV
• 1 jet with secondary vertex tag
• B tag improves S/B 1/6 ?3/1
• Find 15 candidate events in 57.5 pb-1
• Expect 3.8 0.5 background events

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control
signal
?tt5.3 1.9stat 0.8syspb
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Top production cross sections
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Top Mass

• Select l 4 jet events
• Same as cross section, but no b tags
• 33 candidate events
• Method
• 24 combinations in an event
• 2-C fit applied, lowest ?2 is chosen to get mass
  for each event
• A continuous likelihood method is used with
  parameterized mass templates
• Mtop is the minimum of log-likelihood
  distribution
• Systematic uncertainty to improve with
  understanding of detector

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Top mass with b tag

• B tag
• Lower backgrounds
• Improves mass resolution
• Same selection
• Relaxed 4th jet requirement
• 11 candidates
• Work in Progress
• Results by Summer

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Lepton Jets Candidate Events
tt l jet candidate Nov 02 2002 run 153693
event 799494 ? (CMUP) 4 jets
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New Physics??

• Where to look?
• Two Approaches at CDF
• Model driven searches
• Drell-Yan spectrum search
• Leptoquarks
• Doubly charged Higgs
• SUSY
• Signature driven searches
• Dijet spectrum
• CHArged Massive Particles
• Photon final states

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Search in Drell-Yan Spectrum

• High Mass Dileptons
• electrons muons used
• Sensitive to Z and Randall-Sundrum Graviton
• No excess observed

? ?-
ee-
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Search in Drell-Yan Spectrum
Already Improving on Run I!!
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1st Generation Scalar LeptoQuarks

• LQLQ ? ee-qq
• 2 high ET electrons, 2 jets
• 0 events observed
• Background 3.43 events
• M(LQ)gt230GeV/c2 (R1gt220)

• LQLQ ???qq
• 2 high ET jets, large ET
• 42 events observed
• Background 4311 events
• 60ltM(LQ)lt107GeV excl.

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H Search

• Arises in extensions of SM (L-R symmetric)
• Same sign leptons
• Low backgrounds
• Study with less integrated luminosity
• Dielectron channel
• Signal above Z pole
• Low mass used as control
• 0 events observed
• Background 0.60.5
• Binned Search 0 events

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DiJet Search

• Consistent with SM
• Set limits on New Physics
• Axigluons or flavor universal colorons
• 200 lt m lt 1130 GeV/c2
• Excited quarks
• 200 lt m lt 760 GeV/c2
• Color octet techni-rs
• 260 lt m lt 640 GeV/c2
• E6 diquarks
• 280 lt m lt 420 GeV/c2
• W
• 300 lt m lt 410 GeV/c2

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Highest Dijet mass event
Run 152507 event 1222318 Dijet Mass 1364 GeV
(corr) cos q 0.30 z vertex -25 cm
J1 ET 666 GeV (corr) 583 GeV (raw) J1 h 0.31
(detector) 0.43 (correct z)
J2 ET 633 GeV (corr) 546 GeV (raw) J2 h -0.30
(detector) -0.19 (correct z)
CDF Run 2 Preliminary
Run I max 1040 GeV
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CHArged Massive ParticleS

• Stable charged particle that escapes detector
• Massive ? Slow moving
• Use TOF detector
• 7 events observed
• Background 2.93.2 events
• Candidate stop
• NLSP in GMSB
• Isolated M(stop) gt 108 GeV
• non-isolated M(stop) gt 95 GeV
• LEP M(stop)gt95 GeV

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DiPhoton Search

• 2 central photons ETgt13 GeV
• Cosmic and beam halo rejection

• Good agreement with SM
• 0 Diphoton Lepton Events observed

M??
/
ET
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Run Iia Prospects

• Towards the next few years

Event yields per experiment (2 fb-1)
DØ / CDF Run 2a Prediction
Sample Wln Zll WV (Wln, VW,g,Z) ZV (Zll,
VW,g,Z) tt (mass sample, ?1 b-tag)
Run I 77k 10k 90 30 20
Run IIa 2300k 202k 1800 500 800
?MW40 MeV ?Mt 3 GeV
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Summary

• Run 2a is well underway!
• Re-established baseline electroweak measurements
• Top program has been launched!
• Many exotics measurements improve on Run I
  results!
• We look forward to larger datasets and testing
  the Standard Model to even greater precision

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Backup Slides
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AFB backup
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WW cross section backup
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Dilepton backup
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Dilepton backup
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Secondary Vertex Tagging

• Signature of a b decay is a displaced vertex
• Long lifetime of b/c hadrons (c? 450 ?m)
• B hadrons travel Lxy3mm before decay with large
  charged track multiplicity.
• Algorithm
• Look for displaced vertices all combination of
  at least 2 tracks
• Jet is tagged as b-jet if Lxy/?xy gt3 (typical
  ?xy150?m)

?(event tag) 45 ? 1 ? 5
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Ljets backup
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Top Mass backup
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Diphoton Backup

• Backgrounds in lgg
• Wgg
• Zgg
• Zg
• egjet
• P(e fake g)2
• Limit Set
• Mcgt113 GeV

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DY search backup
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Dijet mass backup

• Axigluons or Colorons
• 200 lt m lt 1130 GeV/c2
• Run I200ltmlt 980GeV/c2
• Excited quarks
• 200 lt m lt 760 GeV/c2
• Run I200ltmlt 570580 ltmlt 760
• Color octet techni-rs
• 260 lt m lt 640 GeV/c2
• Run I260ltmlt 480 GeV/c2
• E6 diquarks
• 280 lt m lt 420 GeV/c2
• Run I290ltmlt 420 GeV/c2
• W
• 300 lt m lt 410 GeV/c2
• Run I300ltmlt 420 GeV/c2

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Leptoquark search backup
eenn search

• eeqq search
• Dominant Back.
• Drell-Yan, top

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CHAMP backup
Signal
Signal
Control
W--gten
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H Search
Dominated by DY
OPAL Limit mgt98.5-100.5 depending on coupling
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Higgs Sensitivity

• Status as of 2000
• Studies with Run II ongoing
• Run II simulation
• Run II Efficiencies
• New report expected in June 03