はじめにＣＤＦ実験の成果ＣＤＦ実験の現状

ＣＤＦ実験の今後の計画

CDF 実験の現状と将来

物理学セミナー（大阪市立大学）2002 年 11 月 21 日

金　信弘筑波大学物理学系

For the CDF Collaboration

素粒子と素粒子間の力（素粒子物理標準理論）

（　）内の数字は GeV の単位で書かれた質量

物質を構成する粒子（フェルミオン）

力を伝える粒子（ゲージボソン）

アップ (0.002) 　　　チャーム (1.3) 　　　トップ (175 )ダウン (0.005) 　　　ストレンジ (0.14) 　 ボトム ( 4.2)

クォーク

レプトン

電子 (0.0005) 　　 ミュー粒子 (0.106) 　　タウレプトン (1.8)電子ニュートリノ　　ミューニュートリノ　 　　 タウニュートリノ

　電荷　 2/3 - 1/3

- 1 0

グルオン (0) 　　光子 (0) 　　　Ｗ粒子 (80)　　　　　　　　　　　　　 Ｚ粒子 (91)

強い力 電磁気力 弱い力

質量の起源（ヒッグス機構）

　ヒッグスポテンシャル　 V () = 22 /2+ 4 /4 ( 2 > 0 ( ビッグバン直後 )　　　　　　真空の相転移（対称性の破れ） 2 < 0 ( 現在 )

大統一理論　三つの力（電磁力、弱い力、強い力）は、宇宙創生直後の高温時には対称性が成り立ち、同一の力であった。それが冷えてきたときに対称性が破れて異なる力に見えるようになった。

超対称性理論　すべてのフェルミオン（ボソン）には超対称粒子のボソン（フェルミオン）のパートナーが存在する。この超対称性を仮定すると、三つの力の大統一がある高温状態で成り立つ。　この理論は有望であると考えられている。この理論が正しければ、質量 150GeV/c2 以下のヒッグス粒子が存在するし、また標準理論で期待される以上のＫ中間子、 τ 粒子、Ｂ中間子の稀崩壊が起こる。

ビッグバン宇宙と素粒子物理

　　　　　大統一理論　真空の相転移　粒子反粒子対称性の破れ

CD

F

電弱統一理論　ヒッグス粒子

CDF 実験の主要な成果陽子反陽子衝突実験（米国フェルミ国立加速器研究所）

1987 年　　実験開始1994 年　　トップクォーク発見1998 年　　 Bc 中間子発見2001 年 3 月　実験再開　　　　　　　ヒッグス粒子探索　　　　　　　Ｂ中間子のＣＰ非保存

　トップクォークの物理

MW vs. MTOP

Higgs Mass Constraint

From Mtop(CDF,D0),MW(CDF,D0,LEPII)and other electroweak results,

MHiggs < 215 GeV/c2

at 95% C.L.

Ref. LEP ElectroweakWorking Group, CERN EP/2000-016

ヒッグス粒子（標準模型）の生成断面積と崩壊分岐比

生成断面積 生成断面積ｘ分岐比

CDF Run I VH searches ( 106 pb-1)bbWH 0 bbqqHZW '0/

bbZH 0bbZH 0

Expect: 305 st 6.00.6 dtObserve: 36 st 6 dt

Expect: 600 events Observe: 580 events

Expect: 3.20.7 st Observe: 5

Expect: 39.24.4 st 3.90.6 dtObserve: 40 st 4 dt

VH Production Cross Section Limit

95% CL Limit isabout 30 times higher than SM prediction for Mhiggs = 115GeV/c2.

2TeV 陽子反陽子衝突実験（米国フェルミ国立加速器研究所）

2001 年 4 月～ 2004年　 Run2a ( 2fb-1 )2005 年～ 2008 年　 Run2b ( >13fb-1 )

The CDF Collaboration

Totals112 countries 58 institutions 581 physicists-

North America Europe Asia3 Natl. Labs28 Universities

1 Universities

1 Research Lab6 Universities1 University

4 Universities

2 Research Labs

1 University

1 University

5 Universities1 Research Lab

1 University

3 Universities

Tevatron History and FutureDiscovery of top, Bc, …

MW, Mtop, sin2, … measurements

2000 2002 2004 2006 2008

2 x 1032

cm-2 s-1

5 x 1032

cm-2 s-1

Run : 0 Ia Ib IIa IIb s : 1.8 TeV 1.96 TeV

Tevatron Collider Luminosity

0.1 fb-1 2 fb-1 15 fb-1

Tevatron status

• Tevatron operations started in March 2001– Luminosity goals for run 2a:

• 5-8x1031 cm-2sec-1 w/o Recycler• 2x1032 cm-2sec-1 with Recycler

– Achieved:• 3.8x1031 cm-2sec-1 in October ’0

2• Now recovered from June shutdo

wn to improve p-bar cooling• 120 pb-1 delivered until October ’

02– 90 pb-1 are on tape– 10 – 20 pb-1 used for analyses

shown here (details)

Initial Luminosity

July 01

Now

Integr. Luminosity

Delivered

On tape

120 pb-1

90 pb-1

plans

CDFII Detector

Front End ElectronicsTriggers / DAQ (pipeline)Online & Offline Software

Silicon Microstrip Tracker

Time-of-Flight

Drift Chamber

Plug Calor. Muon

Old

New

PartiallyNew

Muon System

Solenoid

Central Calor.

Detector Performance：SVX

• Silicon detectors:– Typical S/N ~12

– Alignment in R- good• R-z ongoing

Details

Full silicon acceptance is in sight …The last 10% of the job takes the second 90% of the effort (but not time!)

• Commissioning:– L00 > 95%– SVXII >

90%– ISL > 80%

• ISL completing cooling work

BackBack to index

% of silicon ladders powered and read-out by silicon system vs. time

Detector Performance：TOF

• TOF resolution within 10 –20% of 100ps design value– Improving calibrations and

corrections

TOFS/N = 2354/93113

S/N = 1942/4517

Detector Performance： XFT

• XFT: L1 trigger on tracks– full design resolutionpT/p2

T = 1.8% (GeV-1) = 8 mrad

Efficiency curve:XFT cut atPT = 1.5 GeV/cXFT

track

Offline

track

Detector Performance： SVT

Secondary VerTex L2 trigger Online fit of primary VtxBeam tilt alignedD resolution as planned

48 m (33 m beam spot transverse size)

8 VME cratesFind tracks inSi in 20 s with offline accuracy

Efficiency

Onlinetrackimpactparam.

=48 m

80%

90%

soon

Physics with CDF-II• Use data to understand the new detector:

– energy scales in calorimeter and tracking systems – detector calibrations and resolutions– tune Monte Carlo to data

• Use data to do physics analyses – Quality of standard signatures– Rates of basic physics signals– Surprisingly some results are already of relevance

in spite of the limited statistics• summary of a lot of work

list

EM Calorimeter scale

• 638 Z e+e in 10 pb-1

(M) ~ 4 GeV

• Check Z mass in data and simulation after corrections– Central region:

• Mean: +1.2% data, -0.6% sim.• Resolution: +2% simulation

– Forward region (Plug):• Mean: +10/6.6% data, +2.0% simul

ation• Resolution: +4% simulation

Central-central

Central-West plug

Central-East plug

NZ = 247

NZ (W+E) = 391

FB asymmetry

Reconstruct Z ee; measure AFB

Both e ||<1NZ(CC) = 247(M) ~ 4 GeV

One ||<1, one ||>1NZ(CP) = 391 AFB will be an additional

handle in Z’ searches

Both e ||>1

NZ(PP) = 160

Central-Plug Dielectron Mass

Usessiliconto tag e±

charge

Measurements with high Et e±

• Good modeling of observed W e distributions

MET resolution from MB data consistent with Run 1

MET detail

Selectiondetails

Measure •B(WeW cross section:

W*BR(We) (nb) =

2.60±0.07stat±0.11syst ±0.26lum

0.16 soon!

5547 candidates in 10 pb-1

Background (8%):- QCD: 260 ± 34 ± 78- Z ee: 54 ± 2 ± 3- W: 95 ± 6 ± 1

High-Pt muons: Z +• Clear Z +signal

– require COT CMU CMP• •– CDF’s purest muons: ~8

57 candidates 66<M<116 GeVNZ = 53.2±7.5 ±2.7

1

2

CMU

CMP

Measurement of W), R

MT

4561 candidates in 16 pb-1

(require COT•CMU•CMP)12.5% background: - Z : 247 ± 13 - W: 145 ± 10 - QCD: 104 ± 53 - Cosmics: 73 ± 30

R = •(W) / •(Z) = 13.66±1.94stat±1.12syst (1.5 from SM)

(W) = 1.67±0.24stat±0.14syst

•B(W) = 2.70±.04stat±.19syst ±.27lum

Measure a precisely predicted ratio establish tight feedback loop on muon detection, reconstruction, and simulation

Many uncertainties, e.g. lumi, cancel in ratio:

W

• Evidence for typical decay multiplicity in W selections

channel important for new physics searches

Measurements with jets

• Raw Et only:– Jet 1: ET = 403 GeV– Jet 2: ET = 322 GeV

Jet expectationsRaw jet distributions

Hadronic Energy Scale• Use J/ muons to

measure MIP in hadron calorimeters– (Run II)/(Run 1) =

0.96±0.05

Gamma-jet balancing to study jet response fb = (pT

jet – pT)/pT

Run Ib (central): fb= -0.1980 ± 0.0017

Run II (central): fb= -0.2379 ± 0.0028 Plug region corrections in progress

centralcalor. Plug regionPlug region

fb = (4.0 ±0.4)%

q

g q

Measurements with jets

• Jet shapes:– Narrower at higher ET

– Calorimeter and tracking consistent

– Herwig modeling OK

16 pb-1 used for this study

Measurements with low Et ±

trigger improved– pT

> 2.0 1.5 GeV > 5° 2.5°

• Observed rates are consistent with expected increase due the lowering of the thresholds

13 pb-1

NoSilicon100k

= 21.6 MeV

Centralmuons only

15 MeV with Silicon

Material & Momentum Calibration• Use J/’s to understand E-loss

and B-field corrections (scale)/scale ~ 0.02% !

• Check with other known signals

Raw tracks

Correct for material in GEANT

Tune missing material ~20%

Add B scale correction

D0

1S

2S3S

confirm with ee

Meson mass measurements

Bu

CDF 2002 PDG/(2S) 3686.43 ±0.54 　 0.9

Bu 5280.6 ±1.7 ±1.1 0.8

Bd 5279.8 ±1.9 ±1.4 0.2

Bs 5360.3 ±3.8 ± 　　 -2.1 2.12.9

• B masses: (2S)J/ (control)– Bu J/

– Bd J/

– Bs J/ More mass plots

BsJ/

BJ/

18.4pb-1

18.4pb-1

B hadron lifetimes

• Inclusive B lifetime with J/’sFit pseudo-c = Lxy

*FMC*M/pTc

=458±10stat. ±11syst. m (PDG: 469±4 m)

• Exclusive B+J/lifetimec=446 ±43stat. ±13syst. m

(PDG: 502±5 m)

J from B = 17%

# B ~ 154

Trigger selects B’s via semileptonic decays ...

Run II trigger & silicon =>~3 yield/luminosity as in Run I(and likely to improve further with optimization)

1910119candidates

34922candidates

61647candidates

SVT selects huge charm signals!

• L2 trigger on 2 tracks:– pt > 2 GeV

• |D| > 100 m (2 body)• |D| > 120 m (multibody)

• Large charm samples!– Will have O( 107 ) fully reconstructed deca

ys in 2fb-1 data set• FOCUS = today’s standard for huge: 139K D0K-+,

110K D+K-++

– A substantial fraction comes from b decays (next slide)

56320D0

25570D±

Fraction of charm from b decays

• D mesons: – What fraction from B?

• D0: 16.4-23.1%• D*+: 11.4-20.0%• D+: 11.3-17.3%

• Ds+: 34.8-37.8%

GaussianK0S

Range of fract. from B using two extreme resolutions functions:

- single gaussian

- parametrization from K0

S sample

Measure Ds, D+ mass difference

• Ds± - D± mass difference

– Both D (KK) m=99.28±0.43±0.27 Me

V• PDG: 99.2±0.5 MeV

(CLEO2, E691)

– Systematics dominated by background modeling

11.6 pb-1

~1400events

~2400events

Brand new CDFcapability

Measure Cabibbo-suppressed decay rates

(DKK)/(DK) = (11.17±0.48±0.98)% (PDG: 10.83±0.27)–Main systematic (8%): background subtraction (E687, E791, CLEO2)

(D)/(DK) = (3.37±0.20±0.16)% (PDG: 3.76±0.17)•several ~2% systematics

–This measurement has pushed the state of the art on modeling SVT sculpting--essential simulation tools for both B physics program and e.g. high-pT b-jet triggers

Monster Kreflection here ...

Future?- CP violation- mixing- rare decays

Already comparable!

Toward Bs mixing!

#B± = 56±12

B+ D0 +

Next steps:•Reconstruct Bs Ds, Ds •Flavor tagging algorithms•Exploit 3 SVX acceptance, SVT efficiency improvements

We observe hadronic B decays!

Yields understood to ~20% level from detailed simulation

constant

Need fully reconstructed (hadronic) decays to see past first couple of oscillation periods

multiplicative error~ 15% (semileptonic)~ 0.5% (hadronic)

2-body hadronic B decays observed!!

– Yield lower than expected (now improved); S/N better than expected– With 2 fb-1 sample, measuring to ~10º may be feasible, using Fleischer’

s method of relating BsKK and Bd, and using as input

#B = 33±9

B h+ h

—sumBdKBsKKBdBsK

CDF IIsimulation

Width~45MeV

Run II Physics Goals Understanding Electroweak Symmetry Breaking EW Measurements (MW, Mtop) Higgs Boson Search

the Standard Model SUSY

Study CP Violation and the CKM Matrix Sin2Measurement Xs Measurement

Searches for New Phenomena

Study CP Violation and CKM Matrix

Bs mixing measurement is important for complete picture of the Unitary triangle.

CP Violation & CKM Matrix (cont.)

BaBar (Winter 01)(Summer 01)

Belle (Winter 01)(Summer 01)

CDF (Run I)

(sin2)

SM

end of 2003

200 pb-1 (Summer 2003)2 fb-1

With data by next summer, Bs mixing : SM prediction region fully covered.sin2 ~ 0.12

Int. luminosity (pb-1)

ヒッグス粒子探索についての記事

CERN 研究所（ジュネーブ）でヒッグス粒子の候補事象が見えた。これが事実かどうかはフェルミ研究所での陽子反陽子衝突実験で明らかにできる。

Electroweak Precision Measurements

Run IIaEW Meas : MHiggs <215 GeV @95%CLLEP II Higgs Searches : MHiggs > 113 GeV @95%CLLEP II Hint @ MHiggs= 115 GeV

Tevatron Run I :Mtop = 174.3 +- 5.1 GeV/c2

MW = 80.452 +- 0.062 GeV/c2

W (from W high mass tail)2.04 +- 0.15 GeV (CDF), 2.22 +- 0.17 GeV (D0)

SM : 2.0937 +- 0.0025 GeV

今後のヒッグス粒子探索

•MH < 130 GeV/c2

pp →WHX →l +bb + X

•125 < MH < 160 GeV/c2

pp →WHX →l +W* W*+X (like-sign dilepton +jets)

•150 GeV/c2 < MH pp →HX →WW X →l l X

(RUN2A)

(RUN2B)

RUN2A( ～ 2004)　 95 ％信頼度で MH < 120 GeV/c2 検出可能RUN2B(2005 ～ )　 95 ％信頼度で MH < 190 GeV/c2 検出可能　 MH < 180 GeV/c2 の証拠　 (3σ evidence)

95 ％信頼度で検出生成の証拠（３σ ）発見（５ σ ）

テバトロン加速器でのヒッグス粒子探索

2001 年 12月

2004 年 12月

2007 年 12月　

証拠検出可能なヒッグス粒子の質量 MH(GeV/c2 )(95% 信頼度で検出できる MH ）

100 150 200

実験開始 (RUN2a)

実験再開 (RUN2b)

LEP 2 のヒッグス粒子

超対称性理論の軽いヒッグス粒子の質量上限

まとめCDF 実験 RUN2 （ 2001 年～）で以下の成果が期待される。

• 2003 年に Bs mixing の測定ができる。また sin2

• 3 年間の実験で 1000 t t 事象が収集され、 ΔMtop ～ 3GeV/c2 でMtop が測定できる。同時に ΔMW ～ 40 MeV/c2 で M Ｗが測定できる。これらより ΔMH～ 0.3MH でヒッグスの質量を間接的に測定できる。

• 3 年間の実験で– 95% 信頼度で MH < 120GeV/c2 のヒッグス粒子検出可能。

• さらに 3 年間のデータ収集によって– 95% 信頼度で MH < 190GeV/c2 のヒッグス粒子検出可能。– MH < 180GeV/c2 のヒッグス粒子の生成の証拠（ 3σ) 。