The Latest Results of the CDF Experiment

Kazuhiro Yamamoto (Osaka City University)

For the CDF Collaboration

March 26, 2007

JPS Meeting at Tokyo Metropolitan University

CDF Experiment

• Being performed at Tevatron accelerator in Fermilab.

• Proton-antiproton collision at s = 1.96 TeV.

• Run II operation started in March 2001.

Tevatron Accelerator

Main Injector

Tevatron

CDF

DØSciBooNE

CDF II Detector

Tevatron Status

• Accelerator performance– Growing year by year

• Typical parameters– Peak luminosity

2.0 ～ 2.5 x 1032 cm-2s-1

– Weekly integrated lum. 40 pb-1/wk

• Run II record2.923 x 1032 cm-2s-1

Tevatron Status (2)

• Integrated Luminosity

CDF Collaboration

~700 physicists from

12 nations and 61 institutionsMcGill Univ.Univ. of Toronto

Argonne National Lab.Baylor Univ.Brandeis Univ.UC DavisUC Los AngelesUC San DiegoUC Santa BarbaraCarnegie Mellon Univ.Univ. of ChicagoDuke Univ.FermilabUniv. of FloridaHarvard Univ.Univ. of IllinoisThe Johns Hopkins Univ.LBNLMITMichigan State Univ.Univ. of MichiganUniv. of New MexicoNorthwestern Univ.The Ohio State Univ.Univ. of PennsylvaniaUniv. of PittsburghPurdue Univ.Univ. of RochesterRockefeller Univ.Rutgers Univ.Texas A&M Univ.Tufts Univ.Wayne State Univ.Univ. of WisconsinYale Univ.

JINR, DubnaITEP, Moscow

Univ. Karlsruhe

Univ. of Geneva

Glasgow Univ.Univ. of LiverpoolUniv. of OxfordUniv. College London

Univ. of Bologna, INFNFrascati, INFNUniv. di Padova, INFNPisa, INFNUniv. di Roma, INFNINFN-TriesteUniv. di Udine

IFAE, BarcelonaCIEMAT, MadridUniv. of Cantabria

LPNHE, Paris

KHCL

KEKOkayama Univ.Osaka City Univ.Univ. of TsukubaWaseda Univ.

Academia Sinica

USA Canada

Russia

Germany

Switzerland

UK

Italy

Spain

France

Korea

Japan

Taiwan

Top quark pair production

• Top quarks are mainly produced in pairs via strong interaction.

• Top quark decay– ~ 1024 sec, tWb (~100%)

– W decays determine experimental signature

・ di-lepton : 2 jets(2b) + 2 leptons + 2 neutrinos ~ 5%

・ lepton + jets : 4 jets(2b) + 1 lepton + 1 neutrino ~30%

・ all-jets : 6 jets(2b) ~44%

Top quark pair production (2)

• Cross section measurement– Dilepton : clean but small stat.

– Lepton + jets : fairly good S/N and stat.

– All jets : large stat. but poor S/N

New approach in dilepton channel

Lepton (e/) + isolated-track - increase acceptance - include decays (to hadrons)

No discrepancy to the SM was found yet.

(tt) = 9.0 1.3(stat) 0.5(syst) 0.5(lum) pb

(L = 1070 pb-1)

Top mass measurement

• Template method– Evaluate a variable strongly co

rrelated with mt

– Compare data to MC with different mt inputs

• Matrix Element method– Event likelihood by signal and

background probability density

– Maximum likelihood to fit mt, JES(jet energy scale, and Cs(signal fraction)

1

( ; , , )

( ; , )

(1 ) ( ; )

s tN

is tt t

ii

s bkg

L x C m JES

C P x m JES

C P x JES

1 2 1 2

1( ) ( ) ( ) ( ) ( , )P x d y f q f q W x y dq dq

PDF Transfer function

Top mass measurement (2)

• Lepton + Jets channel • All hadronic channel

mt = 170.9 2.2(stat+JES) 1.4(syst) GeV/c2

= 170.9 2.6 GeV/c2

mt = 171.1 3.7(stat+JES) 2.1(syst) GeV/c2

= 171.1 4.3 GeV/c2

At lesat 6 jets with ET > 15GeV|h|<2Good jet shape (Centrality, Aplanarity)1 b-tagsET > 280GeV

Lepton ET (PT) > 20GeVJet ET > 15GeVMissing ET > 20GeV1 b-tagsQCD di-jet veto (0.5 < < 2.5)

Top mass measurement (3)

• Future prospect– Uncertainty of <1% in the next years.

We reached a precision of 1.1% in mt .

Single top production

• Top quark production via electroweak process.

One of the best tests for the standard model Sensitivity to beyond the SM processes (FCNC, W’, 4th family, …) Direct measurement of Vtb Unitarity test of CKM matrix Important background of Higgs search Same final state as that of WH Wbb

s-channelNLO = 0.88 0.11 pb

t-channelNLO = 1.98 0.25 pb

Phys. Rev. D70, 114012 (2004)

Single top production (2)

• Likelihood function analysis

L(x )

psigi (x i)i1

nvarpsig

i (x i)i1

nvar pbkgi (x i)i1

nvar

pisig

N isig

N isig N i

bkgi :indexes input

variable

• Neural network analysis

• Matrix element analysis

Single top hidden behind background uncertainty Makes counting experiment difficultt-channel

s-channel

Still need a little more statistics

Single top production (3)

• DØ declared “evidence”.– Analyses using Boosted decision trees,

Matrix elements, and Bayesian neural networks

Combined result : s+t = 4.9 1.4 pb (3.4 significance) hep-ex/0612052

Electroweak diboson production

• According to the SM, only WW and WWZ vertices are allowed.

• Precise measurement of each coupling is one of the sensitive tests to the SM. Window of new physics

• Multi-lepton final states are major background sources of Higgs, SUSY, and other exotics.

• EW diboson production gives information on trilinear gauge couplings.

W W production

• Two high-pT leptons and ET

Mode WW 52.4 0.1 4.3

Drell-Yan 11.8 0.8 3.1W + jets 11.0 0.5 3.2WZ + ZZ 7.9 0.0 0.8

W 6.8 0.2 1.4t t 0.2 0.0 0.0

Sum Background 37.8 0.9 4.7Number of Expected 90.2 0.9 6.4Number of Observed 95

                                                        ,

(WW) = 13.6 2.3(stat.) 1.6(syst.) 1.2(lum.) pb

NLO calculation : (WW) = 12.4 0.8 pb

hep-ex/0605066

W Z production

W channel Z ee channel

(W)•Br(W) = 19.1 1.0(stat.) 2.4(syst.) 1.1(lum.) pb

NLO : (W)•Br(W) = 19.3 1.4 pb

(Z)•Br(Zee) = 4.9 0.3(stat.) 0.3(syst.) 0.3(lum.) pb

NLO : (Z)•Br(Z) = 4.7 0.4 pbA. Nagano (U. of Tsukuba) et al.

Observation of WZ production

• Decays W and Z provide trilepton signature.

CDF Observed 5.9 signal

1.8(WZ) = 5.0 (stat. + syst.) pb 1.6

NLO calculation : (WZ) = 3.7 0.3 pb

First observation of WZ production

Search for Z Z production

• Four charge-balanced leptons from Z0Z0

(ZZ) < 3.8 pb (95% C.L.)

Z0Z0 e/ candidate

SM NLO calculation : (ZZ) = 1.4 0.1 pb

W mass measurement

• mW : fundamental constant as well as mt in SM and BSM

• Radiative corrections strongly correlated to Higgs mass

2

22 sin (1 )EM

W

F W

mG r

Summer ’06

W mass measurement (2)

• Determine mW by comparing transverse mass (mT) b/w data and MC.

T T T2 ( ) ( ) 1 cosm p p

• Charged-lepton track calibration– Cosmic, J/, , Z

• Calorimeter ET calibration

– E/p, Zee• Hadronic recoil correction

– pT balance in Z

• QED effects

• pT distribution tuning

• Parton distribution

• Charged-lepton track calibration– Cosmic, J/, , Z

• Calorimeter ET calibration

– E/p, Zee• Hadronic recoil correction

– pT balance in Z• QED effects

• pT distribution tuning

• Parton distribution

W mass measurement (3)

• Transverse mass spectra

W e channel W channel

W mass measurement (4)

• Charged lepton ET (PT)

• Missing ET (Neutrino PT)

W mass measurement (5)

• Transverse mass fit uncertainties (MeV)

electrons muons common

Statistics 48 54

Lepton energy scale 30 17 17

Lepton resolution 9 3 3

Recoil energy scale 9 9 9

Recoil energy resolution 7 7 7

Selection bias 3 1 0

Lepton removal 8 5 5

Backgrounds 8 9 0

pT model tuning 3 3 3

PDF 11 11 11

QED corrections 11 12 11

Total systematic 39 27 26

W mass measurement (6)

• Fits to mT, pT, ET, and combine them all.

mT pT ET

Comb.fit stat.

syst.

fit stat. syst.

Fit Stat.

Syst.

e 80493 48 39 80451 58 45 80473 57 54 80477 62

80349 54 27 80321 66 40 80396 66 46 80352 60

Common 26 35 42

Comb. 80417 48 80388 59 80434 65

mW(total comb.) = 80413 48 MeV/c2

33SM Higgs mass : 76 GeV/c2

24

SM / MSSM comparison

hep-ph/0604147 and references are therein.

W mass measurement (7)

• New CDF result is the world’s most precise single measurement.

World average uncertainty reduced ~15%EW global fit : Blue band

mH < 144 GeV/c2 @ 95% C.L.

Observation of Bs0 Oscillation

ms = 17.77 0.10(stat.) 0.07(syst.) ps1

Please see PRL97 242003 and slides of JPS-DPF2006 for the detail.http://www.phys.hawaii.edu/indico/contributionDisplay.py?contribId=743&sessionId=218&confId=3

5 measurement of Bs0-Bs

0 oscillation !

Observation of b and b*

• So far, b(udb) was the only established b-baryon.

• Next accessible baryon : b

b(uub, J=1/2), b

(ddb, J=1/2)

b*(uub, J=3/2), b

*(ddb, J=3/2)

J=1/2

J=3/2

Observation of b and b* (2)

• Reconstruction of the decay chain:

2.0m(b

) = 5808 (stat.) 1.7(syst.) MeV/c2

2.3

1.0m(b) = 5816 (stat.) 1.7(syst.) MeV/c2

1.0

1.6m(b*) = 5829 (stat.) 1.7(syst.) MeV/c2

1.8

2.1m(b*) = 5837 (stat.) 1.7(syst.) MeV/c2

1.9

b(*) b

0 +

c+ +

p + K +

Lb0 reconstruction

• Signals consistent with lowest lying b

states at > 5 significant level.

Search for Higgs boson

• SM Higgs boson at the Tevatron

High mass Higgs (130 ~ 200 GeV/c2)– WW dominant multi-lepton signature

Low mass Higgs (< 130 GeV/c2)– bb dominant reconstruction of 2b jets– gg h bb swamps on QCD backgrou

nd– Vh production is promising

gg h WW qq’ Wh WWW* Xqq Zh ZWW* X

qq’ Wh bb, qq’ bbqq Zh bb, bb, qq bb

Search for Higgs boson (2)

• Recent progress : Zh bb

High-pT opposite-sign dilepton

76GeV < M < 116GeV

Njets 2

At least 1 b-tag Fit 2D-ANN outputs to extract pos

sible signal fraction.

Single b-tag

Double b-tag

Single b-tag

Double b-tag

Search for Higgs boson (3)

• Recent progress : gg h WW

High-pT opposite-sign dilepton

Isolated tracks Large Missing ET

Njet 1

Used Matrix Element calculation to extract possible Higgs signals.

lim/SM ~ 3 at Mh ~160GeV/c2

Search for Higgs boson (4)

• Combined Result (1 fb-1)

• Recent progresses presented in the previous slides are not included in this plot.

• Contribution of Japanese institutes WH lbb (Univ. of Tsukuba,

Waseda Univ.) WH WWW (Osaka City Univ.)

Updates coming soon …

CDF Combination

Summer ’06

Tevatron Combination

Summary

• The Tevatron collider and detectors (CDF and DØ) are running in pretty good shape !

• 2.2 fb-1 has been recorded and ~1.1fb-1 was analyzed.– Some of the latest results were presented.

• Tevatron Run II is scheduled to continue till the end of FY2009, and 6~8fb-1 of integrated luminosity is expected to be obtained.– Can we see any signs of Higgs/SUSY before LHC ?