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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 Electroweak interactions as probe of new Physics

W and Z bosons: W charge asymmetry Z d/dy distribution Z Forward Backward Asymmetry (AFB) Search for Z’e+e-

Top quark: Top Mass Charged Higgs production Flavor Changing Neutral Currents Top Charge

Search for new quark states: Exotic bottom baryon search

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 Lepton+Jets golden channel

using 318pb-1

E. Halkiadakis (now Rutgers University professor)

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 yearCurrent and future workPlan for public result

Analysis completed and received best Rochester undergraduate thesis award

G. Yu, S. Field , Y. S. Chung

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W Charge Asymmetry u quark carries higher fraction of proton momentum!A(yW ) =

d + / dyW −d− / dyW

d + / dyW +d− / dyW≈

u(x1)d(x2 )−d(x1)u(x2 )u(x1)d(x2 ) +d(x1)u(x2 )

anti-proton direction proton direction

Get constraints on the PDF’s 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

B.Y. Han, A. Bodek, Y. S. Chung, E. Halkiadakis, K. McFarland

x1,2 =MW

se±yW

**

V-A impactsW production kinematicsW decay kinematics

P =(1±cos * )2

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W Charge Asymmetry Analysis method: Number of W vs yW

Use MET for P: 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:

wt1,2± =

P±(cos1,2* ,y1,2 , pT

W )±(y1,2 )P±(cos1

* ,y1, pTW )±(y1) + P±(cos2

* ,y2 , pTW )±(y2 )

P±(cos * ,yW , pTW ) =A{(1mcos * )2 +Q(yW , pT

W )(1±cos * )2}

MET

Acceptance and smearing

QCD Background subtraction from dataUse new technique of fitting e isolation shape

Charge misidentification using Z e+e- data

q(p)+q(p)

q(p)+q(p)

q(p)+q(p)

q(p)+q(p)

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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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d/dy distribution of the Z boson Probe high momentum fraction of the

proton at high rapidity: Use Plug-Plug region to reach |y|<2.8! Analysis uses 850pb-1

J.Y Han, A. Bodek, H. Budd, W. Sakumoto, Y. S. Chung

d(γ* / Z)dy =

Nsig(y)−Nbkg(y)AZ(y)εZ(y)εtrig(y)εzvtx(y)L

central electron ID efficiency ~83%, ~96%plug electron ID efficiency ~83%Z vertex luminosity acceptance ~96%

ID triggerZ efficiency in central-central ~90% ~100%Z efficiency in central-plug ~70% ~95%Z efficiency in plug-plug ~71% ~98%

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d/dy distribution of the Z boson QCD background predictions:

Isolation fitting method Use data to get signal and

background isolation shape (subtract W+jets from background selection using MC for shape and data for normalization)

Systematics: Background estimation Material

Remaining: 1fb-1

Electroweak backgrounds dependence of ID efficiencies

Already started public result procedure

Zcc0.420.09%

(Zee) : 251.15± 1.04(stat.)0.31(sys.) pb

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Measurement of Z AFB

Dilepton decay of γ*/Z has forward backward angular asymmetry AFB=(NF-NB)/(NF+NB) Probe V-A nature of weak

interaction New technique:Response

Matrix inversion Rij=P(observed in bin i | true

value in bin j) Observed =R * True True = R-1 * Observed True = R-1 * (Observed - bckg)

J. Lee, G. De Lentdecker, K. McFarland

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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, sin2w

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Measurement of Z AFB

Other method: increase sensitivity by fitting cos* 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 cos* distribution

Public result with 1fb-1 around end of summer

J. Lee, G. De Lentdecker, K. McFarland

d̂ ( ff → e+e−)dcos * ∝ CF 1+ cos *( )

2+CB 1−cos *( )

2⎡⎣

⎤⎦• Acc(cos * )

Fit function minimizing CF and CB

AFB =3 CF −CB( )4 CF +CB( )

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FCNC in the Top sector FCNC in the SM only

allowed by penguins BR<10-12

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 l, Z ll (trilepton

+ 2 jets + MET)

J. Gimmell, U. Husemann, (K. McFarland), P. Tipton, Harvard, UCLA

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FCNC in the Top sector Backgrounds:

Z+jets: 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 X W+b or W+b (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

L+J: 2 algorithm 3) Flavor of b jet: JetQ

algorithm Measure dilution in dijet

data

V. Boisvert, W. Hopkins (undergrad), M. Schwarz (undergrad),K. McFarland, MSU

?

b or b ?b or b ?

?

Reco bReco b

True b

True b

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Top Charge Dilution in dijet data:

Look at correlation between and away jet

Corrections: Non-b fraction on side

and away jet side Template fitting using

data b c 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

Jet axis

b tagged

Soft PTrel

Away Jet

b tagged

x

x

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

In SUSY get 5 Higgs bosons, including H

Direct production is small at Tevatron

Look for ttWb Hb Low tan, H cs

Use Top mass 2 fitter M(Wl)=80.4GeV/c2,

unconstrained M(Wjj) Deciding on b tagging

requirements M(H) resolution improvement

using 5th leading jet Sensitivity studies underway

G. Yu, Y.S. Chung, A. Bodek, U. of Chicago

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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

measuringasymmetry

the closest asymmetry to data

assumedsample

F1 min( )2

new assumedsample

Fn

reconstructionInputdata

YesNo

if no,

(yW) vs. PDF

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Rediscover the Top quark Use Top physics to establish

techniques: Cross section b tagging Background treatment

What about top charge? Measure em couplings using ttγ

(hep-ph/0106341)

R=(γ in t prod)/(γ 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 95%CL LHC: need 10fb-1 to measure

charge to 10%

γ

γ

γ

γ