JPS 2005 Spring

2005/4/6

CDF Run-II 実験の最近の結果
受川 史彦

CDF

CDF Collaboration
筑波大学
物理学系 / 数理物質科学研究科

日本物理学会 第60回年次大会
2005年3月24－27日
東京理科大学 野田キャンパス

Tevatron Accelerator• New 120/150 GeV Main Injector replaced Main Ring
– Higher intensity of protons and antiprotons.

• Tevatron operates
with 36 x 36 bunches(had been 6 x 6)
• Increased CM energy
1.8 TeV to 1.96 TeV

Run II started inMarch 2001

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Tevatron Luminosity : Run-II

瞬間ルミノシティ

1×1032

年ごとの積分値• Peak luminosity
1.24 x 1032 cm-2 s-1(Mar 21, 2005)• Delivered luminosity~ 850 pb-1
• Recorded luminosity~ 660 pb-1

Run-II CDF Detector
Many detector components
are brand-new• Tracking system• Silicon detectors• Main drift chamber• FE electronics• Trigger/DAQ• Plug calorimeter• Extended muon coverage• TOF system
Retained good momentum
resolution & lepton ID.

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最新の物理の結果• 電弱相互作用 （W boson の質量，Gauge boson 対生成）
• Top quark の物理 （生成断面積，質量，W helicity）• Higgs 粒子の探索 （３つのチャンネル）• B 粒子の物理（b Æ s 遷移を主に）あらゆる結果を網羅することは不可能
http://www-cdf.fnal.gov/を参照されたし．

Electroweak Physics

CDF RUN IIPRELIMINARY

CDF RUN IIPRELIMINARY

CDF RUN IIPRELIMINARY

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W Mass Measurement
Muons
CDF RUN IIPRELIMINARYElectronsmT fit

CDF RUN IIPRELIMINARY

mT(μν)(GeV)

mT fitmT(eν)(GeV)

ET fitpT fit

CDF RUN IIPRELIMINARY

CDF RUN IIPRELIMINARY
pT(μ)(GeV)

pT(ν)(GeV)

Fits still blinded

W boson 質量測定の誤差
CDF RUN IIPRELIMINARY

Total uncertainty (76 MeV) already lower than Run 1 (79 MeV)
質量の中心値 Æ 夏までに公表の予定

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tGauge boson pair production
Unified electroweak theory :Non-Abelian gauge structure.
→ self-coupling among gauge bosons.

                                           

ET

150
100500432100η

100-1-2200-3-4300

φ

W + Photon ProductionPhotons detected > 7 GeV
Check 3-body mass (l ν γ) for brems.

More direct test : angular distributions → radiation amplitude zero

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Top Quark• Observed by CDF in Run-I data, 100 pb-1.
• Tens of events reconstructed,measurements limited by statistics.
• Run-II data should allow more detailed studies.

Signature :• Two W and two b• W to lepton + νor, W to quarks.
• b-jets tagged withlifetime or lepton.

Top quark production cross section

Di-lepton channel
CDF 197 pb-1

Jet multiplicity distribution
entries/jet bin

Event count per jet bin
CDF II - 197 pb80-1

WW + WZ + ZZ

70+ Drell-Yan

60+ fakes
50+ tt (σSM = 6.7 pb)

40
30
20
1000

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1≥2Njet6

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2005/4/6

Top cross section

CDF
162 pb-1

生成点付近の拡大図

Jet の数の分布

Many other measurements with various techniques.

Many channels and techniques.

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Top Quark MassCombine with W mass,probe Higgs indirectly.

tWh0W Wb
∆MW α MT2?
W WW
∆MW α ln MHW?
New Physics

World average : Run I only
Run-II expectations, ~3 GeV

CDF/DØ2 fb-1 goal

hep-ex/0404010

Top mass measurements

Both b-quark jets tagged

Dynamical likelihood method(K. Kondo, J.Phys.Soc.Jap. 57, 4126,1988)

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W helicity in top decays

either left-handed (WL) or longitudinally polarized (W0)

Lepton angular distribution in
W rest frame :Backward peak for left-handed W.
→ smaller momentum in lab.
Also reconstructs cosθ∗Higgs 粒子の探索
崩壊分岐比

生成断面積

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終状態： W + two b jets
Analysis similar to top search, tag b jets.
But BG higher than in top search.

SM signal x10 (115 GeV)

終状態： 同電荷のレプトン対

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終状態： レプトン対，large missing energy，no jets
Main BG : electroweak W pair production

Leptons + missing ET system mass

Opening angle of leptons

Higgs 粒子生成の探索のまとめ

実験の上限値

標準理論の予言値

上限： 理論値の数十倍

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2005/4/6

B physics : does the unitarity triangle close?

CDF Run II Preliminary
0*+lepton+D (D*+lepton+D2RS

4000

Signal ~ 13362

WS200001.7

1.8
1.9
2M(K π+) (GeV/c )Candidates per 1 MeV/c

Candidates per 5 MeV/c

CDF Run II Preliminaryexcluded)

2

6000

2000
Signal ~ 3779

1500
1000
50002

CDF Run II Preliminary

103

1010

110F. Ukegawa, CDF

2Candidates per 25 µm

Candidates per 25 µm

10fit prob. = 0.754
AllB0B
Backgrounds

100.2

CDF Run II Preliminary*+Combined lepton-D0Combined lepton-D3

0.14
0.16
0.18
2- +∆M(K π+π+s -K π ) (GeV/c )2fit prob. = 0.100
AllB0B
Backgrounds

10110-1-1-0.1
00.1
0.2
0.3
Pseudo-proper Decay Length (cm)

-0.1
00.1
0.2
0.3
Pseudo-proper Decay Length (cm)12

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New physics in b → s transition ?

00b) B → φK s

600

Entries/ps

1
0.5
0-0.5

0.0 < r ≤ 0.5-11c)

0.5
0-0.5
-1-7.50.5 < r ≤ 1.0-5-2.5

0∆t (ps)

2.557.5(Nqξ=−1−Nqξ=+1)/(Nqξ=−1+Nqξ=+1)

Raw Asymmetry

Belle : PRL 91, 261602 (2003)qξf=+1qξf=−1400
200
00.50<r≤0.50-0.50.5<r≤1.00.5
0-0.5-8-6-4-20∆t(ps)

2468

CDF 実験での b → s 遷移の検証 (SUSY?)
B-factory 実験と相補的な測定・観測量

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Vtd for B0d,bfor B0•Vtss• FCNC
• Helicity suppressed.
• B.F. very small.
SM predictions for B.F.

d, sw
tbd, stwl+l-w

l+w Z/γl-Run-II Di-muon data : CDF

種々の共鳴状態を高統計で再構成

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One candidatein the overlap region of B0dand B0s mass windows.

B.R. < 1.9 x 10-7 for B0d
B.R. < 7.5 x 10-7 for B0s@ 95% C.L.
PRL 93, 032001 (2004)
Previous CDF limits :B.R. < 8.6 x 10-7 for B0d
B.R. < 2.6 x 10-6 for B0s
PRD 57, 3811 (1998)
近々 update の予定 (360 pb-1), 3倍程度の改善を予期-1candidates per 5.0 MeV/c2

CDF Run II Preliminary
60Bs → J/ψ φ
203±15 sig.
candidates

50

Fit prob: 93.4%

candidates per 50 µm

CDF Run II Preliminary
L ~ 260 pb
datam(Sig)m(Bkg)

4030

CDF 240 pb-1

Bs → J/ ψ φ
10data3ct(Sig)ct(Bkg all)102ct(Bkg S)
Fit prob: 26.9%

1020
1001
5.3

5.4

5.52(µµKK) mass, GeV/c-0.1

0.0

0.1

0.2

0.3

ct, cmFuture : look for CP-violation, ~0 expected in SM, arg(Vts).

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CDF Run II Preliminary

L~180 pb

Bs → J/ ψ φ

χ2 Prob: 7.0 %

0.016

-1

CDF Run II Preliminary

L~180 pb

Bs → J/ ψ φ

χ2 Prob: 47.5 %

0.018

0.014

candidates per 50 µm

0.012

0.014

0.01

0.012

0.008
0.006

0.01

0.004

0.008

0.002

0.006
0.004

00.002-0.002-1-0.8-0.6-0.4-0.2

0cosΘT

0.2

0.4

CDF Run II Preliminary
0.014

0.6

L~180 pb

0.8

10-3-2-10ΦT

123-12

Bs → J/ ψ φ-1

CDF Run II Preliminary

0.016χ Prob: 48.9 %

0.012
0.01
0.008
0.006

10103L ~ 260 pb

Bs → J/ψ φdata
Sig AllSig Light2Sig Heavy
Bkg Long-lived
Bkg Short-lived

10Fit prob: 26.4%

0.004
0.002
0-1

-0.8

-0.6

-0.4

-0.2

0cosΘK

0.2

0.4

0.6

0.8

11-0.1

0.0

0.1

0.2

0.3

ct, cm

B signals from CDF SVT triggers : full reconstruction
CDF Run II Preliminary-1

L ≈ 355 pb

CDF Run II Preliminary_

Number of entries / 10 MeV/c 2

Number of entries / 10 MeV/c 20B+ → D π+
5625 candidates

1500-1

L ≈ 355 pb
B0 → D π+

6157 candidates

10001000

5600

500

04.8

55.2
5.4
5.6
5.8_2K+ π π+ mass [GeV/c ]

6200
500

0
4.8

55.2
5.4
5.6
5.8
__2K+ π π π+ mass [GeV/c ]Understand proper time resolution and flavor tagging

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測定の手順

Measure flavor tagging using B+ and B0 decays-1

L ≈ 355 pb

CDF Run II Preliminary+0.30B+ → J/ψ K+, B → D π+0.20.2

0.10.1

Asymmetry

Asymmetry

0.3

0-0.1
-0.2
-0.3
00.05

0.1

00-0.1Data
Fit projection

-0.3
0.15

0.2

proper time [cm]

_B0 → J/ψ K*0, B → D π+-0.2

Data
Fit projection-1

L ≈ 355 pb

CDF Run II Preliminary

00.05

0.1

0.15

0.2

proper time [cm]εD2 = (1.1 ± 0.2)%

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CDF Run II Preliminary

1600

Entries per 5 MeV/c2

JPS 2005 Springl D-sl+ D+s

1400
1200-1

L = 360 pb+N(lDs) = 4355 ± 941000800600
4002000

Total hadronic : 900±431.85

1.90

1.95
2.00
2mass(KKπ) [GeV/c ]Total semileptonic 7700±150

Measurement along the way: cτ (B0s) = 479 ± 29 (stat.) ± 5 (syst.) µm(PDG = 438 ± 17 µm)

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フーリエ解析：振動が起こっていれば振幅Aが１となる

Best single experiment limit is 10.9 ps-1 (sensitivity 15.2 ps-1)

Impact on World Average Sensitivity

We increase sensitivity by 0.4 ps-1, limit is unchanged

Improvements for summer 2005
• more signals (more decay modes, better trigger)• same-side (kaon) tagging Æ could be a factor of 2-4• improve ct resolution

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Summary
Tevatron Run-II in progress since 2001 :• Machine luminosity vastly improved,delivered > 850 pb-1 to each experiment.
• CDF recorded ~650 pb-1.
– 6×Run-I total. More to come.

• Top production reconfirmed, new precision / measurements coming.
• Electroweak physics :– Precision MW → indirect Higgs mass. Triple-Gauge couplings.

• Enhanced B physics capabilities :– Many ways to test CKM triangle, b Æs transition in particular.

• Expect to collect ~2 fb-1 in the near future (early 2006?),
and to make some significant measurements before LHC.
Surprises welcome, too!

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