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CDF実験の現状と将来
金信弘
筑波大学物理学系
For the CDF Collaboration
物理学セミナー（大阪市立大学）
2002年11月21日
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
素粒子と素粒子間の力（素粒子物理標準理論）
物質を構成する粒子（フェルミオン）
クォーク
アップ(0.002)
ダウン(0.005)
電荷
2/3
- 1/3
チャーム(1.3)
トップ(175 )
ストレンジ(0.14) ボトム( 4.2)
レプトン
電子(0.0005)
電子ニュートリノ
ミュー粒子(0.106)
ミューニュートリノ
タウレプトン(1.8)
タウニュートリノ
-1
0
力を伝える粒子（ゲージボソン）
強い力
グルオン(0)
電磁気力
弱い力
光子(0)
Ｗ粒子(80)
Ｚ粒子(91)
（）内の数字はGeVの
単位で書かれた質量
質量の起源（ヒッグス機構）
ヒッグスポテンシャル
V (f) = m2f2 /2 + lf4 /4 ( l
m2 > 0 (ビッグバン直後)
真空の相転移（対称性の破れ）
m2 < 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
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)
WH 0    bb
Expect: 305 st
6.00.6 dt
Observe: 36 st
W / Z  H 0  qq '  bb
Expect:
600 events
6 dt
Observe:
580 events
ZH 0       bb
ZH 0   bb
Expect: 3.20.7 st
Observe: 5
Expect: 39.24.4 st
3.90.6 dt
Observe: 40 st
4 dt
VH Production Cross Section Limit
95% CL Limit is
about 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
North America
3 Natl. Labs
28 Universities
Europe
1 Research Lab
6 Universities
1 University
1 Universities
4 Universities
Totals
112 countries
 58 institutions
 581 physicists
-
2 Research Labs
1 University
1 University
Asia
5 Universities
1 Research Lab
1 University
3 Universities
Tevatron History and Future
Discovery of top, Bc, …
MW, Mtop, sin2b, … measurements
2 x 1032
cm-2 s-1
Tevatron Collider Luminosity
2 fb-1
0.1 fb-1
2000
Run : 0
s :
Ia
1.8 TeV
Ib
5 x 1032
cm-2 s-1
2002
2004
15 fb-1
2006
IIa
IIb
1.96 TeV
2008
Tevatron status
• Tevatron operations started in
March 2001
– Luminosity goals for run 2a:
Initial Luminosity
July 01
• 5-8x1031 cm-2sec-1 w/o Recycler
• 2x1032 cm-2sec-1 with Recycler
Now
– Achieved:
• 3.8x1031 cm-2sec-1 in October ’02
• Now recovered from June
shutdown 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)
plans
Integr. Luminosity
Delivered
120 pb-1
90 pb-1
On tape
CDFII Detector
Muon System
Central Calor.
New
Old
Solenoid
Partially
New
Muon
Plug Calor.
Time-of-Flight
Drift Chamber
Front End Electronics
Triggers / DAQ (pipeline)
Online & Offline Software
Silicon Microstrip
Tracker
Detector Performance：SVX
• Silicon detectors:
– Typical S/N ~12
– Alignment in R-f 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
% of silicon ladders powered and read-out
by silicon system vs. time
Back
Back to index
Detector Performance：TOF
• TOF resolution within 10 –20%
of 100ps design value
– Improving calibrations and
corrections
S/N = 1942/4517
S/N = 2354/93113
TOF
Detector Performance：XFT
Offline
track
XFT
track
Efficiency curve:
XFT cut at
PT = 1.5 GeV/c
• XFT: L1 trigger on tracks
– full design resolution
 DpT/p2T = 1.8% (GeV-1)
 Df = 8 mrad
Detector Performance：SVT
8 VME crates
Find tracks in
Si in 20 ms
with offline
accuracy
Secondary VerTex L2 trigger
 Online fit of primary Vtx
 Beam tilt aligned
 D resolution as planned
48 mm (33 mm beam spot transverse size)
Online
track
impact
param.
90%
Efficiency
80%
s=48 mm
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
list
• summary of a lot of work
EM Calorimeter scale
• 638 Z  e+e in 10 pb-1
 s(M) ~ 4 GeV
FB asymmetry
NZ = 247
Central-central
• Check Z mass in data and
simulation after corrections
– Central region:
• Mean: +1.2% data, -0.6% sim.
• Resolution: +2% simulation
Central-West plug
– Forward region (Plug):
• Mean: +10/6.6% data, +2.0%
simulation
• Resolution: +4% simulation
NZ (W+E) = 391
Central-East plug
Reconstruct Z  ee; measure AFB
Both e ||<1
NZ(CC) = 247
s(M) ~ 4 GeV
Uses
silicon
to tag e±
charge
Both e ||>1
NZ(PP) = 160
Central-Plug Dielectron Mass
One ||<1, one ||>1
NZ(CP) = 391
AFB will be an additional
handle in Z’ searches
Measurements with high Et
±
e
• Good modeling of observed
W e distributions Selection
details
MET resolution from
MB data consistent
with Run 1
MET detail
Measure s•B(We
0.16 soon!
W cross section:
sW*BR(We) (nb) =
2.60±0.07stat±0.11syst ±0.26lum
Background (8%):
- QCD: 260 ± 34 ± 78
- Z ee: 54 ± 2 ± 3
- Wt: 95 ± 6 ± 1
5547 candidates in 10 pb-1
High-Pt muons: Z m+m
• Clear Z m+m signal
– require COT•CMU•CMP
– CDF’s purest muons: ~8l
m1
CMU
m2
CMP
57 candidates 66<M<116 GeV
NZ = 53.2±7.5 ±2.7
Measurement of sB(Wm), R
4561 candidates in 16 pb-1
(require COT•CMU•CMP)
12.5% background:
- Z mm: 247 ± 13
- Wt: 145 ± 10
- QCD:
104 ± 53
- Cosmics: 73 ± 30
s•B(Wm) = 2.70±.04stat±.19syst ±.27lum
Many uncertainties, e.g. lumi, cancel in ratio:
R = s•B(Wm) / s•B(Zmm) =
13.66±1.94stat±1.12syst (1.5s from
SM)
 G(W) = 1.67±0.24stat±0.14syst
MT
Measure a precisely predicted ratio  establish tight feedback loop on
muon detection, reconstruction, and simulation
W  t
• Evidence for typical
t decay multiplicity
in W t selections
 t channel important
for new physics
searches
Measurements with jets
• Raw Et only:
– Jet 1: ET = 403 GeV
– Jet 2: ET = 322 GeV
Jet expectations
Raw jet distributions
Hadronic Energy Scale
• Use J/y muons to
measure MIP in
hadron
calorimeters
– (Run II)/(Run 1) =
0.96±0.05
q
g
g
Plug region
central
calor. Plug region
q
 Gamma-jet balancing to study jet response
 fb = (pTjet – pTg)/pTg
Run Ib (central):
fb= -0.1980 ± 0.0017
Run II (central):
fb= -0.2379 ± 0.0028
 Plug region corrections in progress
Dfb = (4.0 ±0.4)%
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 m±
 y trigger improved
– pTm > 2.0  1.5 GeV
 Df> 5°  2.5°
• Observed yrates are consistent
with expected increase due the
lowering of the thresholds
13 pb-1
No
Silicon
100k y
Central
muons
only
15 MeV
with
Silicon
s= 21.6 MeV
Material & Momentum Calibration
• Use J/y’s to understand E-loss
and B-field corrections
 s(scale)/scale ~ 0.02% !
• Check with other known signals
D0
Add B scale correction
Tune missing material ~20%
Correct for material
in GEANT
confirm
with
gee
U
1S
2S
Raw tracks
3S
mm
Meson mass measurements
• B masses:

–
–
–
y(2S)J/ypp (control)
Bu J/yK
Bd J/yK* (K*Kp
Bs J/yf
(fKK
BsJ/yf
18.4pb-1
More mass plots
DPDG/s
0.9
y(2S)
CDF 2002
3686.43 ±0.54
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
-2.1
2.9
BJ/yK
Bu
18.4pb-1
B hadron lifetimes
• Inclusive B lifetime with J/y’s
J/y from B = 17%
Fit pseudo-ct = Lxyy*FMC*My/pTy
ct=458±10stat. ±11syst. mm
(PDG: 469±4 mm)
• Exclusive B+J/yK lifetime
ct=446 ±43stat. ±13syst. mm
(PDG: 502±5 mm)
# B ~ 154
Trigger selects B’s via semileptonic decays ...
1910119
candidates
Run II trigger & silicon =>
~3 yield/luminosity as in Run I
(and likely to improve further with
optimization)
34922
candidates
61647
candidates
SVT selects huge charm
signals!
• L2 trigger on 2 tracks:
– pt > 2 GeV
• |D| > 100 mm (2 body)
• |D| > 120 mm (multibody)
56320
D0
• Large charm samples!
– Will have O( 107 ) fully
reconstructed decays in 2fb-1
data set
• FOCUS = today’s standard for huge:
139K D0K-p+, 110K D+K-p+p+
– A substantial fraction comes
from b decays (next slide)
25570
D±
Fraction of charm from b decays
• D mesons:
– What fraction from B?
D0:
D*+:
D+:
Ds+:
•
•
•
•
K0
S
16.4-23.1%
11.4-20.0%
11.3-17.3%
34.8-37.8%
Range of fract. from
B using two extreme
resolutions functions:
- single gaussian
- parametrization
from K0S sample
Gaussian
Measure Ds, D+ mass difference
• Ds± - D± mass difference
– Both D  fp (fKK)
 Dm=99.28±0.43±0.27
MeV
• PDG: 99.2±0.5 MeV
(CLEO2, E691)
– Systematics dominated by
background modeling
Brand new CDF
capability
11.6 pb-1
~1400
events
~2400
events
Measure Cabibbo-suppressed decay rates
G(DKK)/G(DKp) = (11.17±0.48±0.98)% (PDG:
10.83±0.27)
–Main systematic (8%): background subtraction (E687, E791, CLEO2)
Already (PDG:
comparable!
G(Dpp)/G(DKp) = (3.37±0.20±0.16)%
3.76±0.17)
• several ~2% systematics
–This measurement has pushed theFuture?
state of the art on modeling SVT sculpting--essential
simulation tools for both B physics- program
and e.g. high-pT b-jet triggers
CP violation
- mixing
- rare decays
Monster Kp
reflection here ...
Toward Bs mixing!
#B± = 56±12
constant
B+  D0 p+
multiplicative error
~ 15% (semileptonic)
~ 0.5% (hadronic)
Need fully reconstructed (hadronic) decays
to see past first couple of oscillation periods
We observe hadronic B decays!
Yields understood to ~20% level from
detailed simulation
Next steps:
•Reconstruct Bs Dsp, Ds fp
•Flavor tagging algorithms
•Exploit  3 SVX acceptance,
SVT efficiency improvements
2-body hadronic B decays observed!!
CDF II
simulation
Width
~45MeV
#B = 33±9
—sum
BdKp
BsKK
Bdpp
BsKp
B  h+ h
– Yield lower than expected (now improved); S/N better than expected
– With 2 fb-1 sample, measuring g to ~10º may be feasible, using Fleischer’s
method of relating BsKK and Bdpp, and using bas input
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
 Sin2bMeasurement
 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.)
With data by next summer,
 Bs mixing : SM prediction region fully covered.
 dsin2b ~ 0.12
200 pb-1 (Summer 2003)
end of 2003
2 fb-1
CDF (Run I)
BaBar (Winter 01)
(Summer 01)
Belle (Winter 01)
(Summer 01)
SM
Int. luminosity (pb-1)
(sin2b)
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
Tevatron Run I :
Mtop = 174.3 +- 5.1 GeV/c2
MW = 80.452 +- 0.062 GeV/c2
Run IIa
EW Meas : MHiggs <215 GeV @95%CL
LEP II Higgs Searches :
MHiggs > 113 GeV @95%CL
LEP II Hint @ MHiggs= 115 GeV
GW (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
(RUN2B)
95％信頼度で検出
生成の証拠（３σ）
発見（５σ）
pp →HX →WW X →l l X
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)
(RUN2A)
テバトロン加速器での
ヒッグス粒子探索
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)
2001年12月
実験再開(RUN2b)
2004年12月
2007年12月
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sin2bが誤差で測定
できる。
• 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MＷ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)。

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