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CDFCDF の最新結果の最新結果武内勇司 武内勇司 (( 筑波大筑波大 ))

for CDF collaborationfor CDF collaboration

特定領域「フレーバー物理の新展開」研究特定領域「フレーバー物理の新展開」研究20112011

鹿の湯ホテル鹿の湯ホテルJul. 2Jul. 2ndnd, 2011, 2011

ContentsContents•CDF/Tevatron statusCDF/Tevatron status

•Top physicsTop physics–ttbar spin correlation (ttbar spin correlation ( 武政＠若手セッション武政＠若手セッション ))

•B physics (B physics ( 三宅三宅 ))

•Higgs search Higgs search （永井）（永井）

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Tevatron Run II

TevatronProton-antiproton collisions at √s = 1.96 TeVShutdown on Sep. 30, 2011Final dataset: ~10 fb-1 expected for physics

CDFD0

Chicago

TEVATRON

MAIN INJECTOR

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The CDF II Detector

Silicon vertex detector (1+5+2 layers)Central drift chamber (8 super layers) 1.4T solenoidGood particle identification (K,)Central/Wall/Plug calorimetersScintillator+drift chamber muon detectors

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Peak luminosity4.14×1032 cm-2 s-1

Weekly integrated luminosity84 pb-1/week

Annual integrated luminosity2.5 fb-1 (US FY 2010)

Tevatron Status

FY02FY03

FY04FY05

FY06

FY07FY08

FY09

FY10FY11

12.6×1032 cm-2 s-1(ATLAS)

~1fb-1/month(ATLAS)

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Integrated LuminosityDelivered 11.3fb-1, Recorded 9.3fb-1

ATLAS

ATLAS x tt ratio

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jets

HF

WZ

W Z

WW tt WZ

singletop

ZZ

Higgs

NewPhysics?

Physics Programs at Tevatron

SM processWZ,ZZ, Single-Top, ...

Top quark physics

Precise measurementW mass, ...

Heavy flavor phyics(bb)100s

Higgs search

Search for new physics

7TeV pp

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Top quark physics at CDF

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Heaviest elementary particleplay a special role in EWSB?

provides new test ground on Standard ModelDirect access to bare quark

Top quark decays before hadronization

Decays as a naked quark Information on spin polarization and momentum at its

production is directly transferred to decay products

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Dominant process at Tevatron

10%~20%

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Categorize ttbar events into 3 decay types according to W decay mode

Dilepton• 2 lepton• 2 b-jet• MET

All Hadronic• 6 jet(2 b-jet)

Lepton+Jet• 1 lepton• 4 jet(2 b-jet)• MET

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343 cand./5.1fb-1

~105 bkg.

S/N~2.3

105 cand./35pb-1

~21.6 bkg.

S/N~3.7

ATLAS

727 cand./4.3fb-1(4j, w/btag)~126 bkg.

S/N~4.8

402 cand./35pb-1

~93 bkg.

S/N~3.3

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Consistent with predictionBetter uncertainty than theoretical uncertainties!All channel, w/, w/o b-tag are consistent

Consistent with Br(t→Wb)~100%

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Top mass

Mt=1.09 GeV/c2 (0.63%)

Mt<1GeV/c2 can be reachable

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Top charge (Qt=2/3 vs 4/3)

P-value for SM: 0.134P-value for XM: 0.00014

l+jet channell-b paring kinematics: Ppairing=83%

Jet charge kinematics: PJQ=61%

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top quark decays before losing polarization

V-A couplingflight direction of down-type fermion from W carries 100% spin information of parent top quark

can “see” top quark spin at its production

top spin polarization vector in top rest flame

down-type

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Information on Wtb VertexReally W boson?

Really V-A?

In SM

tb

Left

tb

Long

-1 -0.5 0 0.5 10

0.2

0.4

0.6

0.8

left-handed

longitudinal

right-handed

sum (SM)

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Consistent with tWb vertex

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Also presence of new physics could make asymmetry

NLO prediction: Interference between LO and NLO

+2

V

+2

ForwardBackward

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RunII 5.3fb-1 l+jets results(1)yt(=yt-ytbar)

Background subtracted, then unfolded back to parton level.

Attbar = 0.1580.074

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RunII 5.3fb-1 l+jets results(2)Look at parton-level asymmetry as functions of yt and Mttbar

Attbar(yt >1.0) = 0.611 0.210 0.147Attbar(Mttbar >450GeV) = 0.475 0.101 0.049

To be compared to Apred(Mttbar >450GeV) = 0.088 0.013

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Inherit Afb of parent ttbar

0jet and 1jet events can be used as control sample to validate bkg shapes

RunII 5.1fb-1 dilepton results(1)

0jet

1jet

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Subtracting background

Apply corrections for acceptance and dilution due to reconstruction

Attbar = 0.42 0.15(stat) 0.05(stat)

RunII 5.1fb-1 dilepton results(2)

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F-B asymmetry at other experiments

Background subtracted asym.Attbar = 8 4(stat) 1(syst) %To be compared: APred=1+2

-1 %In pp collision

quark from valence, anti-quark from sea: quark tends to larger x

Afb>0 |t|-|tbar| has positive asym.AC=0.060 0.134(stat) 0.026(syst)

They claim same sensitivity as Tevatron with 1/fb!

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ここまでの Summary Tevatron は今年の 9 月までの運転

CDF の full dataset は，約 10/fb になる見込み

Top quark properties are consistent with SM so farExcept for forward-backward asymmetry at top pair production

Top quark properties are being measured more and more precisely, not to overlook any hint of new physics.

Uncertainty in top mass measurement: < 1 GeV/c2 Uncertainty in pair production cross-section measurement is now better than theoretical uncertainties

Top quark 対生成の機構は ,Tevatron と LHC で異なるCross-section や forward-backward asymmetry, Mtt 共鳴 , ttbar spin correlation などは，対生成の機構に依存

Tevatron の解析もまだまだ重要

引き続き CDF の B の物理（三宅）， Higgs 探索 ( 永井 ) のトークをお楽しみください