Ongoing physics analyses and future projects

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Ongoing physics analyses and future projects

• Véronique Boisvert
• Marshak Fellow
• For the CDF Rochester group

Rochester DOE Site visit July 18th 2006
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Focus of the group
Phys. Rev. Lett. 96, 211801 (2006) J. Lee, G. De
Lentdecker Already referred to in 3 papers
Public result for the matrix element method in
LeptonJets golden channel using 318pb-1 E.
Halkiadakis (now Rutgers University professor)

• Electroweak interactions as probe of new Physics
• W and Z bosons
• W charge asymmetry
• Z ds/dy distribution
• Z Forward Backward Asymmetry (AFB)
• Search for Z?ee-
• Top quark
• Top Mass
• Charged Higgs production
• Flavor Changing Neutral Currents
• Top Charge
• Search for new quark states
• Exotic bottom baryon search

Analysis completed and received best Rochester
undergraduate thesis award G. Yu, S. Field , Y.
S. Chung
Phys. Rev. Lett. 96, 042003 (2006) R. Eusebi
(now FNAL Lederman fellow), A. Hocker (now FNAL
scientist) Already referred to in 2 papers New
analysis started G. Yu, Y.S. Chung
Legend Past year Current and future work Plan
for public result
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W Charge Asymmetry
B.Y. Han, A. Bodek, Y. S. Chung, E. Halkiadakis,
K. McFarland

• u quark carries higher fraction of proton
  momentum!

• Get constraints on the
  PDFs of the proton
• Important QCD information
• Helps to better model production rapidity of
  heavy systems (W, Z, tt, etc.)
• Reduces systematic uncertainty from acceptance
  corrections

?anti-proton direction proton direction?

• V-A impacts
• W production kinematics
• W decay kinematics

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W Charge Asymmetry

• Analysis method Number of W? vs yW
• Use MET for Pn missing Pz!
• Use MW constraint to get 2 possible yW
• Weight each of them depending on
• Angular distribution
• W cross section
• Depends on A!
• Iterate!
• Araw ? Atrue Corrections

q(p)q(p)
q(p)q(p)
q(p)q(p)
q(p)q(p)

• QCD Background subtraction from data
• Use new technique of fitting e isolation shape
• Charge misidentification using Z? ee- data

• MET
• Acceptance and smearing

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W Charge Asymmetry

• Systematics
• E scale (ET(e?), MET)
• PDF uncertainty
• Angular Distribution
• W cross section
• Background
• Material effect, Acceptance
• 1fb-1 prediction
• Investigating East-West Asymmetry discrepancy
• Expect public result with 343pb-1 by end of summer

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ds/dy distribution of the Z boson
J.Y Han, A. Bodek, H. Budd, W. Sakumoto, Y. S.
Chung

• Probe high momentum fraction of the proton at
  high rapidity
• Use Plug-Plug region to reach ylt2.8!
• Analysis uses 850pb-1

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ds/dy distribution of the Z boson

• QCD background predictions Isolation fitting
  method
• Use data to get signal and background isolation
  shape (subtract Wjets from background selection
  using MC for shape and data for normalization)
• Systematics
• Background estimation
• Material
• Remaining
• 1fb-1
• Electroweak backgrounds
• h dependence of ID efficiencies
• Already started public result procedure

Zcc 0.42?0.09
? (Z?ee) 251.15 1.04(stat.)?0.31(sys.) pb
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Measurement of Z AFB
J. Lee, G. De Lentdecker, K. McFarland

• Dilepton decay of g/Z has forward backward
  angular asymmetry
• AFB(NF-NB)/(NFNB)
• Probe V-A nature of weak interaction
• New techniqueResponse Matrix inversion
• RijP(observed in bin i true value in bin j)
• Observed R True
• True R-1 Observed
• True R-1 (Observed - bckg)

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Measurement of Z AFB

• Backgrounds
• QCD backgrounds
• New technique fitting isolation shape using
  templates
• Electron data at Z pole
• Jets high pt electron data, remove W/Z events
• Electroweak backgrounds use MC
• Systematics
• E scale and resolution, Response matrix,
  Background, material, PDF
• 364pb-1 result already public
• Updating with 1fb-1
• Extract coupling constant, sin2qw

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Measurement of Z AFB
J. Lee, G. De Lentdecker, K. McFarland

• Other method increase sensitivity by fitting
  cosq in mass bins
• Worry about acceptance, smearing, QED radiation
  and fit convergence
• Backgrounds
• Use tools from matrix inversion method
• Systematics
• Use results from matrix inversion method worry
  about NLO QCD distorsion of cosq distribution
• Public result with 1fb-1 around end of summer

Fit function minimizing CF and CB
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FCNC in the Top sector
J. Gimmell, U. Husemann, (K. McFarland), P.
Tipton, Harvard, UCLA

• FCNC in the SM only allowed by penguins
• BRlt10-12
• New Physics strongly enhances BR (10-3-10-4)
• MSSM, 2HDM, dynamical EWSB, warped ED, etc.
• Looking at tt ? Wb Zc
• Standard W? jj, Z ? ll (dilepton from Z 4
  jets)
• Also W ? ln, Z ? ll (trilepton 2 jets MET)

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FCNC in the Top sector

• Backgrounds
• Zjets use sophisticated Alpgen MC and validate
  with data distributions
• Z 4 jets
• Zbb 2 jets
• Zcc 2 jets
• SM Top
• Diboson (WZ)
• Jets faking leptons
• For greater sensitivity separate events according
  to
• 1 b tag
• 0 b tag
• Optimize event selection based on best expected
  limit (Feldman-Cousins including systematics)

Heavy Flavor fraction not well modeled, new use
templates and fit the data to get fraction
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Top Charge
V. Boisvert, W. Hopkins (undergrad), M. Schwarz
(undergrad),K. McFarland, MSU

• X? Wb or Wb (and cc)?
• If exotic q-4/3, better EW fit
• hep-ph/9810531, hep-ph/9909537
• Ingredients
• 1) Charge of W
• Charge of lepton
• 2) Pairing between W and b
• Dilepton M2lb value
• LJ c2 algorithm
• 3) Flavor of b jet JetQ algorithm
• Measure dilution in dijet data

?
?
b or b ?
b or b ?
Reco b
Reco b
True b
True b
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Top Charge

• Dilution in dijet data
• Look at correlation between m and away jet
• Corrections
• Non-b fraction on m side and away jet side
• Template fitting using data
• b ? c ? m fraction (MC)
• B mixing fraction (MC)
• Extrapolate from dijet to tt
• Backgrounds
• Investigated if backgrounds mimic more SM top or
  exotic quark
• Mostly symmetric between SM top and exotic

• Confidence Limit extraction
• Using Profile Likelihood method and studied
  sensitivity of
• dilution uncertainty very sensitive
• amount of backgrounds not very sensitive
• etc.
• Working hard to get preliminary public result
  with 1fb-1 by end of summer

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Charged Higgs Search from Top decays
G. Yu, Y.S. Chung, A. Bodek, U. of Chicago

• In SUSY get 5 Higgs bosons, including H?
• Direct production is small at Tevatron
• Look for tt?W?b H?b
• Low tanb, H ??cs
• Use Top mass c2 fitter
• M(W?ln)80.4GeV/c2, unconstrained M(W?jj)
• Deciding on b tagging requirements
• M(H) resolution improvement using 5th leading jet
• Sensitivity studies underway

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Conclusion

• Rochester members involved in crucial CDF
  analyses that will
• potentially lead to NP discovery!
• remain relevant even after the LHC turn on!
• Isolation fitting method for the QCD background
• Precise W rapidity method
• b flavor tagging in high pt environment
• Students and post-docs primary authors of complex
  and challenging projects
• New analyses and/or novel techniques!
• Rochester scientists and faculty provide the
  necessary infrastructure to the realization of
  these analyses and the education of the young
  members!

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Backups
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W charge asymmetry
s(yW) vs. PDF
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Rediscover the Top quark
g

• Use Top physics to establish techniques
• Cross section
• b tagging
• Background treatment
• What about top charge?
• Measure em couplings using ttg (hep-ph/0106341)
• Rs(g in t prod)/s(g in t decay)
• Irreducible bckg from radiation off q,q (not an
  issue at LHC)
• Tevatron need 20fb-1 to rule out -4/3 at 95CL
• LHC need 10fb-1 to measure charge to 10

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