B崩壊の物理
飯嶋 徹
名古屋大学
2010年2月23日
特定領域「フレーバー物理の新展開」研究会

Bファクトリーの3大物理成果
高輝度電子・陽電子衝突実験で切り開く物理• B崩壊におけるCP対称性の破れの発見と小林益川理論の検証• b/ c /τ rare process における新物理探索– B稀崩壊：B Xs γ, K(*) ll, τν– D中間子混合

A02計画研究居波– τ LFV 高感度探索 ~O(10-8)• 新しいハドロン共鳴の相次ぐ発見

Super-KEKB/Belle II 実験へ

森、有田

測定器開発

Bファクトリーの新たな可能性

We welcome your contribution
Visit our home page !
http://www.hepl.phys.nagoya-u.ac.jp/public/new_hadron/index.html

Success of the B-factories
2008 Nobel Prize in Physics

M. Kobayashi

T. Maskawa

Similar plot by the UT-fit group

Still room for modifications by NP.
Rare B decays are powerful tools !

4

KEKB加速器の成果
世界最高のルミノシティーを達成
クラブ衝突L peak = 21.1 /nb/s
L day =1479 /pb/day

L total =955 /fb

2000年1月

2009年6月

2009年12月までに >1ab-1 を達成

5

Luminosity at the B-factories~950 fb-1
4S: 710fb-1
5S: 86.fb-1
3S: 3.3 fb-1
2S: 6.7 fb-1
1S: 7.6 fb-1
Off peak: 90 fb-1

~800M BBKEKBfor Belle~553 fb-1~ 470M BB
PEP-IIfor BaBar

4S: 433fb-1
3S: 30fb-1
2S: 14fb-1
Off peak: 54fb-1

Stopped inApril 2008
6B→K*ll崩壊• FCNC 崩壊• 極めてクリーンなプローブ• 様々な測定量

+γ, Z
W−

sb

−

ν−

W−bW+tt

+sAFB ∝ ℜ C10* ( sC9eff ( s ) + r ( s )C7 ) q2 分布–– Forward-backward asymmetry– Isospin asymmetry
etc.

L-

θ

B

K*L+657 M BB,

384M BB,submitted to PRL, arXiv: 0904.0770

PRD79, 031102(R) (2009)

C7=-C7SM
C7=-C7SMSMSM
C9C10=-(C9C10)SM
CDF

三宅さんのトーク

C7=-C7SM&C9C10=-(C9C10)SMAFB exceeds SM ?

B-→ l- νb

−W−H−uν• Within SM, proceed via W annihilation.

Helicity suppression

Br ( B → e ν )  Br ( B → µ ν )  Br ( B → τ ν )~10-11~10-7

Determination of fB|Vub|=f B 190 ± 13 MeV

HPQCD,
0902.1815v2

BrSM (τν ) = (1.20 ± 0.25) ×10−4

Vub = (4.32 ± 0.16 ± 0.29) ×10−3 HFAGICHEP08

Sensitive also to NP (charged Higgs )8

Analysis for B→lν
S/N

Hadronic tags
Btag→D(*)π/ρ etc.
πKTagging side

Reconstruct the recoil B to tag- B production- B flavor/charge- B momentumπ
Semileptonic tags
Btag→D(*)lν etc.
D(*)

v
−Inclusive tags
Effe+Btag
e-4-vector sum of PID tracks(except for signal tracks)

Υ(4S)

±

Bsigv
Signal side: Bsig→ l ν- Detect charged track(s)- Missing energy (mass) due to ν’s- No extra activities in EM
calorimeter (E ECL(extra) )9Bτν Candidate Event
B+ g D0 π+K+ π- π+ πB- g τ - νe-νν

2009/03/19Toru Iijima @ Hints0910

Signal shape : Gauss + exponential
Background shape : second-order polynomial

Belle Results

Signal + Hadronic Tag (449M BB)

background

PRL 97, 251802 (2006)+0.56+0.46
Br( τν) =[1.79-0.49(stat)-0.51(syst)] × 10-4+7.6+5.5
NS = 24.1-6.6(stat)-6.3(syst)

3.5σ (incl. syst.)

in all EECL region.

BackgroundBτν Semileptonic Tag (657M BB)

SignalBELLE-CONF-0840, arXiv:0809.3834+0.38+0.35
Br( τν) =[1.65-0.37(stat)-0.37(syst)] × 10-4+36+21NS =154-35(stat)-22(syst)

3.8σ (incl. syst.)
2009/03/19

Toru Iijima @ Hints0911

Constraint on Charged HiggsNaïve world averageBr( τν) =[1.73 ± 0.35] × 10-4

BrSM ( τν) = [1.20 ± 0.25] × 10-4

Effect of Charged Higgs

Based on fB from HPQCD and |Vub| fromHFAG (BLNP, ICHEP08)

W. Hou, Phys. Rev. D48, 2342 (1993)=Br BrSM × rH ,
 mB2 tan β 2
1rH = 12εβm1+tanH0tan β =vuvd

Constraint on charged Higgs

2Type-II 2HDMSUSY Loop correction
ε0=0 for Type-II 2HDM

95%CL exclude

12However….
Can we rely on lattice for fB ?
Can we rely on |Vub | ?

2009/03/19

Toru Iijima @ Hints0913

If we use CKM fit…
+0.096Br( τν)fit = (0.937-0.015) × 10-4+0.179
Br( τν)fit = (0.786-0.083) × 10-4τν is not included in the fit

HFAG summer08(1.51±0.33)x10-4

CKM2008(1.73±0.35)x10-4
2009/03/19

Toru Iijima @ Hints09

14

mb tan β

B→D τ νcbBD τ ν is also sensitive to H+, andcomplementary to Bτν.
•Relatively large Br ~0.8%•Different theory systematics:

H+/W+mτ tan βτ+ντ– free from Vub and fB uncertainties.
– depends on the BD form factors,R( D) =Br ( B → Dτν )Br ( B → Dν ) Three-body decay permits the study of decay distributions which
discriminate between W+ and H+ exchange. U. Nierste, S. Trine, S.Westhoff
PRD78, 015006 (2008).

 Universality between H-b-c, (Dτν), H-b-u (τν), H-b-t (LHC) can betested.
arXiv:0906.1652 (hep-ph/)A. Cornell, A. Deandrea, N. Gaur, H. Itoh, M. Klasen, Y. Okada

15

B→D τ ν w/ by Belle• 657M BB• Hadronic tags.
• Extract signals in (MM2, EECL)
distribution.
• Simultaneous extraction ofDτν/D*τν.
R(%)

NsSignif.

D0 τ ν+26.3 3.8(4.4)
+11.0
98.6
70.2 +18.9-25.0-18.0 -9.1

D+ τ ν+7.7+6.3
17.2
47.6 +21.6-6.9-19.3 -5.4

D*0 τ ν+6.2
46.8 +10.6-10.2 -7.23.9(5.2)
99.8 +22.2-22.3

D*+ τ ν+5.8
48.1 +14.0-12.3 -4.1

25.0 +7.2-6.3

First observation of BD* τ ν
w/ inclusive tag
PRL99, 191807 (2007),

B + → D 0τ +ν

B 0 → D −τ +ν

2.6(2.8)

4.7(5.9)Dτν signal

D*τν cross talk16

B→Dτν: BaBar+BelleMy Naïve Average• Belle R(D) =[60 ± 14(stat) ± 8(syst)]%• BaBar R(D) = [41.6 ± 11.7(stat) ± 5.2(syst)]%• Belle+BaBar R(D) =[49 ± 10]%

Constraint on Charged Higgs
form factors
Br ( B → Dτν ) =G τ Vcb
2F B

mB2g S = 2 tan 2 βmH

2f ( FV , FS , g S )(Type-II 2HDM)

H. Itoh, S. Komine and Y. Okada,
PTP 114, 179 (2005), hep-ph/0503124.
D l ν form factor reported by BaBar;
arXiv: 0807.4978, 0809.0828

R( D) =Br ( B → Dτν )Br ( B → Dν )Type-II 2HDM
95%CL excludedby Bτν95%CL excludedby BDτν

17

Sensitivity to charged Higgs
Charged Higgs bosontan β

5 σ discovery sensitivityAtlasBelle II, 5 ab-1
Belle II, 50 ab-1
excluded currently (Br(B→τν)) @ 95.5%
5σ discovery, Belle II, 5 ab-1
5σ discovery, Belle II, 50 ab-1

mH+ [GeV]
Belle II Br(B→τν)) sensitive to H+ at large mH+ and tan β
at low tan β B → Xs γ constraints the parameters
Belle II reach @ L can be parametrized:tan β ≥ 5 ·√(0.5 ab-1/L) ·[1·10-4GeV-2 · (m - 90 GeV)2 + 12.2]

B.GolobBファクトリーのアップグレード
目標ルミノシティー = 8×1035cm-2s-1• RFの増強より高いビーム電流• 衝突点の改良 より小さいビームサイズ

Super-KEKB
L=8x1034cm-2s-1
ILER/ＨER=2.96/1.70A
βy* = 0.22mm∫Ldt =50ab-1∫Ldt =10ab-1

Present KEKB
L=2x1034cm-2s-1
ILER/ＨER=1.62/0.95A
βy* = 5.9mm

Three year shutdown to:
4install new beam pipe
4increase RF
4modify IR+ Belle upgrade∫Ldt =1ab1

2010

2015

2020

Physics with O(1010) B, τ, charm

19

Physics Reach at Super-KEKB/Belle
5ab-1

50ab-1∆S(φK0)

0.22

0.073

0.029

∆S(η’K0)

0.11

0.038

0.020

CP asymmetry
in B→KKK, φK and η’K

Deviation from SM

0.3∆S(KSKSKS)

0.33

0.1050.037∆S(KSπ0γ)0.320.100.03Br(Xsγ)

13%ACP(Xsγ)

0.058

0.010.005

C9 [AFB(K*ll)]

---

11%

4%

C10 [AFB(K*ll)]

---

13%

4%

Br(B+ → K+νν)<9Br(SM)

33ab-1 for 5σ discovery

Br(B+ →τν)

3.5σ

10%

Br(B+ →µν)

<2.4Br(SM)4.3ab-1 for 5σ discovery

Br(B+ → Dτν)

---

7.9%

2.5%

Br(τ →µγ)<45<30<8Br(τ →µη)

<65<20<4Br(τ → 3µ)<209<10<1∆sin2φ10.026

0.0160.012∆Φ2 (ρπ)

68°ー95°3°1°∆Φ3( Dalitz)

20°

7°

2.5°

∆Vub (incl.)

7.3%

6.6%

6.1%

●★

(3σ discovery lim.)
0.1
Presentexp. limits
0.03

5ab-1
0.01

3%

■AFB

Belle’06(~0.5ab-1)

50ab-150ab-1

Forward-Backward
1
10100
Asymmetryin BK*ll-1
Integ. luminosity (ab )Upper limits
q2(GeV2/c2)

X10-9

CKM at 50ab-Integ. Lum.（ ab-1 ）Reach of B factories
Upgraded KEKB

20Colliding bunches

7GeV
e- 2.1 A

Nano-Beam 4GeV
e+ 3.7 A
SuperKEKBNew Superconducting /permanent final focusing
quads near the IPReplace long TRISTAN
dipoles with shorter
ones (HER).
Add / modify rf systems
for higher currents.

Redesign the HER arcs tosqueeze the emitance.

Low emittance gun

Low emittance electrons toinject

TiN coated beam pipe withantechambers

Low emittance positrons toinject
New positron target / capture
sectionx40 Gain in Luminosity21

Belle Upgrade

Better background tolerance
Better performance

ECL
Wave sampling + pureCsI crystal(endcap)

日本,ロシア, US

KL/µ detection
RPC → Scintillator+SiPM(endcap)

日本,台湾,ロシア

PIDThreshold Aerogel + TOF→ TOP + Aerogel-RICH
日本,スロベニア,USCDC
Super small cell
Longer lever arm
New Dead time freereadout andhigh speed
computing systems

日本

SVD
4-lyr DSSD → 6lyr DSSD 日本,韓国,スペイン,ドイツ,チェコ,ポーランド,オースト(option: striplet / pixel ) リア,US,インド

Technical Design Report 作成中

22

New Collaboration
2004.06: SuperKEKB LoI
2008.01: KEK ロードマップ
2008.03 1sr プロトコラボレーションミーティング
2008.10 Detector design study report
2008.12: 新実験コラボレーションキックオフ(1st. meeting)
13 ヶ国, 43 研究機関 、スポークスマン選考中
ドイツ、チェコ、インド、US などから新たな参加
2010.3.31-4.2 第5回コラボレーションーティング

新コラボレーション名Belle II23

まとめ• KEKB/Belle 実験 世界最高ルミノシティーによる成果総括へ– CPV, 小林益川理論の検証– B稀崩壊– τ 物理• Super-KEKB/Belle II 実験– 目標ルミノシティー：8x1035cm-2s-1– B物理
Heavy flavor による– タウ物理
新物理の探索と解明– ハドロン物理（QCD）

新しい物質の存在形態

物理は豊富。新たな価値観も。

世界最高ルミノシティー加速器の増強と、ユニークな最先端測定器によって、電子・陽電子衝突加速器実験のフロンティアを切り開く。
若手の参加を歓迎しています。