bファクトリー実験の最新結果 -...

K+π +

π −e−

π −π +

Missing

飯嶋徹

名古屋大学

2006年8月3日“素粒子物理学の進展２００６”

Bファクトリー実験の最新結果&

今後の展望

2

The KEKB Collider

e+ source

Ares RF cavity

Belle detectorSCC RF(HER)

ARES(LER)

e- (8.0GeV) × e+ (3.5GeV)⇒Υ(4S) →BB⇒Lorentz boost: βγ = 0.425

Finite crossing angle- 11mrad ×2

Operation since 1999.

Peak luminosity1.65 x 1034 cm-2s-1 !

3

Belle測定器

4

Belle Collaboration

13 countries, 57 institutes, ~400 collaborators

IHEP, ViennaITEPKanagawa U.KEKKorea U.Krakow Inst. of Nucl. Phys.Kyoto U. Kyungpook Nat’l U. EPF Lausanne Jozef Stefan Inst. / U. of Ljubljana / U. of MariborU. of Melbourne

Aomori U.BINPChiba U.Chonnam Nat’l U.U. of CincinnatiEwha Womans U.Frankfurt U.Gyeongsang Nat’l U.U. of HawaiiHiroshima Tech.IHEP, BeijingIHEP, Moscow

Nagoya U.Nara Women’s U.National Central U.Nat’l Kaoshiung Normal U.National Taiwan U.National United U.Nihon Dental CollegeNiigata U.Osaka U.Osaka City U.Panjab U.Peking U.U. of PittsburghPrinceton U.RikenSaga U.USTC

Seoul National U.Shinshu U.Sungkyunkwan U.U. of SydneyTata InstituteToho U.Tohoku U.Tohuku Gakuin U.U. of TokyoTokyo Inst. of Tech.Tokyo Metropolitan U.Tokyo U. of Agri. and Tech.Toyama Nat’l CollegeU. of TsukubaUtkal U.VPIYonsei U.

5

Integrated Luminosity

PEP-IIfor BaBar

As of July 24, 2006

KEKBfor Belle

KEKB + PEP-II

KEKB/Belle: 630.0 fb-1

PEP-II/BaBar: 378.8 fb-1

Total = 1000fb-1

109 BB pairs !

6

Our Motivation

sin2φ1 history(1998-2005)

Q. What is the main source ofCP violation ?

A. Kobayashi-Maskawa phaseIS the dominant source !

Paradigm shift !

Q. Are there deviations from theCKM picture ? (e.g. newCP-violating phases)

7

Talk OutlineOver-constrain the unitarity triangle.– Precise measurement of φ1, φ2, φ3, Vcb, Vub, Vtd.

Compare sin2φ1 between tree and penguin diagrams.

Search for new physics effects in – Rare B decays

– LFV τ decays Belle @ ICHEP06#abstracts#talks

+ Future

8

Over-constraining the UT

9

Kobayashi-Maskawa (1973)cos sin'sin cos'

C C

C C

d ds s

θ θθ θ

⎛ ⎞⎛ ⎞ ⎛ ⎞= ⎜ ⎟⎜ ⎟ ⎜ ⎟−⎝ ⎠ ⎝ ⎠⎝ ⎠

GIM

Flavor eigenstate

Mass eigenstate

CKM

'''

ud us ub

cd cs cb

td ts tb

V V Vd ds V V V sb bV V V

⎛ ⎞⎛ ⎞ ⎛ ⎞⎜ ⎟⎜ ⎟ ⎜ ⎟= ⎜ ⎟⎜ ⎟ ⎜ ⎟

⎜ ⎟ ⎜ ⎟⎜ ⎟⎝ ⎠ ⎝ ⎠⎝ ⎠

KM W－

d(s,b)uV*ud(s,b)

u c td s b

⎡ ⎤ ⎡ ⎤ ⎡ ⎤⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎣ ⎦ ⎣ ⎦ ⎣ ⎦

3X3 unitarity triangle has 3 rotational angles and one comlex phase. CPV

CP in KL π+π-

10

The Unitarity Triangleud us ub

cd cs cb

td ts tb

V V VV V VV V V

⎛ ⎞⎜ ⎟ =⎜ ⎟⎜ ⎟⎝ ⎠

( )

2 3

2 2 4

3 2

1 ( )2

1 2(1 ) 1

A i

A

A i A

λ λ λ ρ η

λλ λ λ

λ ρ η λ

⎛ ⎞− −⎜ ⎟⎜ ⎟− − + Ο⎜ ⎟⎜ ⎟− − −⎜ ⎟⎝ ⎠ WolfensteinKM

* * * 0ud ub cd cb td tbV V V V V V+ + =

2φ

3φ 1φρ

η

*

*tb

cb

td

cd

VV VV

*

*ubud

cd cb

VV V

V

1

/ SB J K

unitarity

ψ→

,B ππ ρπ→

B DK→

B-B mixinguB X ν→

2

( ) 1 ( )2

λρ η ρ η⎛ ⎞

= −⎜ ⎟⎝ ⎠

11

The Golden Decay 0 / SB J Kψ→

bcs

W + /J Ψ

d d SK0B

c

0 / SB J Kψ→• Tree

0Bb

d

0B

t

t

W + W −

b c

sW +

/J Ψ

d dSK

c

0 0 / SB B J Kψ→ →• Box + Tree

12

CP Violation in B Decays

• (The initial) B0 and B0 exhibits different quantum interference.

0B / SJ Kψie φ

0B

0B

Different !

0Bie φ−

0B

0B

/ SJ Kψ

B at t=0CP mirrorB at t=0

13

Method to study CPV

e-(8.0GeV) e+(3.5GeV)

B0

B0B0

Produce B and B by e-e+ collision

-

K-

B flavor tagging

J/ψ

KS

-

+ Detect B J/ψ Ks

t=0 Measure time-dependence

Asymmetric collision w/ high luminosityDetector w/ good vertex & particle id. capability

14

ttCPCPV in BV in B00 decaysdecays

Mixing-induced CPV Direct CPV

e.g. for J/ψ KsS = −ξCPsin2φ1 = +sin2φ1A = 0to a good approximation(ξCP : CP eigenvalue)

e.g. for J/ψ KsS = −ξCPsin2φ1 = +sin2φ1A = 0to a good approximation(ξCP : CP eigenvalue)

(A = −C a la BaBar)

15

BB00 J/J/ψψ KK00 : combined result: combined result

sin2φ1= 0.642 ±0.031 (stat) ±0.017 (syst)A = 0.018 ±0.021 (stat) ±0.014 (syst)

previous measurementsin2φ1= 0.652 ± 0.044

(386 M BB pairs)

B0 tag_B

0 tag

532 M BB pairs_ _

Belle preliminary BELLE-CONF-0647BELLE-CONF-0647

O. TajimaO. Tajima

16

2006: BaBar + Belle2006: BaBar + Belle

Consistency with Vub, φ3/γ R. Kowalewski (next speaker)

Belle 2006: B0→π+π－ decay (CP asymmetry)

0

100

200

300

q = +1q = −1

(a)

No

. o

f π

+π

- ev

en

ts

-1

0

1

-5 0 5∆t (ps)

π+π

- asym

metr

y

(b)

04.010.061.005.008.055.0

±±−=±±+=

ππ

ππ

SA

first error: stat., second: syst.

17background subtracted

π+π－yields

π+π－asymmetry

Large Direct CP violation (5.5σ)

Large mixing-induced CP violation (5.6σ)

confidence level contour

H. IshinoH. Ishino

BELLE-CONF-0649BELLE-CONF-0649_

532M BB1464±65 signal events

18

-0.4-0.2

00.20.40.60.8

11.21.4

0 100 200 300 400 500

BelleBaBar

Aππ

-2

-1.5

-1

-0.5

0

0.5

1

0 100 200 300 400 500BB

– (×106)

Sππ

History of B0→π+π－ decay

(C = −A)

2.3σ diff. btw. Belle and BaBar

ICHEP2006: BaBar(ICHEP2006: BaBar(ππππ//ρπρπ//ρρρρ) + Belle() + Belle(ππππ//ρρρρ))

α/φ2 = [93 ]°+11− 9 consistent with a global fit w/o α/φ2

αGlobal Fit = [ 98 ] º+5-19

19

20

Status of CKM fit 2006

No inconsistency found so far...

21

Is this enough ?

No,A little tension between |Vub| and φ1.Need improvement of φ3– We should first determine the apex by tree-level

processes; |Vub| + φ3

– Then compare it to others;• Bd mixing and CPV• Bs mixing and CPV• εK and B(K πνν)

|Vub|e-iφ3 |Vtd|eiφ1

|Vcb|

22

Determination of |Vub|

Inclusive B Xu l ν Exclusive B π l ν

Like to see consistency with better precision.

23

CP Violation in b s Penguin

24

CPV in b s Penguin Processes• Heavy particles may be mediated in the quantum loop.

• In SM, CPV(B0 φKs) = CPV(B0 J/ψKs)

• If a new particle carries a quantum new phaseCPV(B0 φKs) ≠CPV(B0 J/ψKs)

b s

s

sg

φNP ?

d d SK

φ0B

bc

sW

/J Ψ

d d SK0B

c

CP dN1 PA (t) sin2( + ) sin(∆ t)mφφ= ×

25

Belle 2006: Belle 2006: BB00 φφKK0 0 signalsignal

B0 mass

B0 momentum

_532M BB

(bkg subtracted)

φ K+K−, KS π+π−

φ K+K−, KS π0π0

φ KSKL, KS π+π−

114 ± 17 φKL signal114 ± 17 φKL signal

307 ± 21 φKS signal307 ± 21 φKS signal

Three modes

New !

BELLE-CONF-0647BELLE-CONF-0647

Belle 2006: tBelle 2006: tCPCPV in V in BB00 φφKK00

“sin2φ1” = +0.50 ± 0.21(stat) ± 0.05(syst)A = +0.07 ± 0.15(stat) ± 0.06(syst)


_532M BB

∆t distribution and asymmetry

φKS and φKL combinedbackground subtractedgood tags∆t –∆t for φKL 26

Consistent with the SM (~1σ lower)Consistent with Belle 2005

(Belle2005: “sin2φ1” = +0.44±0.27±0.05)

The most precise measurement now

Consistent with the SM (~1σ lower)Consistent with Belle 2005

(Belle2005: “sin2φ1” = +0.44±0.27±0.05)

The most precise measurement now

unbinned fitSM


27

Belle 2006: Belle 2006: BB00 ηη''KK0 0 signalsignal_

532M BB

1421 ± 46 η'KS signal1421 ± 46 η'KS signal

451 ± 41 η'KL signal451 ± 41 η'KL signal

B0 momentumB0 mass (bkg subtracted)

Belle 2006: tBelle 2006: tCPCPV in V in BB00 ηη''KK00



_532M BB


First observation of tCPV (5.6σ) in a single b s mode Consistent with the SMConsistent with Belle 2005

(Belle 2005: “sin2φ1” = +0.62±0.12±0.04)

First observation of tCPV (5.6σ) in a single b s mode Consistent with the SMConsistent with Belle 2005

(Belle 2005: “sin2φ1” = +0.62±0.12±0.04)

η''KS and η''KL combinedbackground subtractedgood tags∆t –∆t for η''KL BELLE-CONF-0647BELLE-CONF-0647

28

29

Belle 2006: tBelle 2006: tCPCPV in V in BB00 KKSSKKSSKKSS



185 ± 17 KSKSKS signal185 ± 17 KSKSKS signal

B0 mass

_532M BB


background subtracted

good tags


30

Status at Summer 2005

31

2006: 2006: φφ11 with with bb ss PenguinsPenguinsSmaller than b ccs in all of 9 modesSmaller than b ccs in all of 9 modes

Theory tends to predictpositive shifts(originating from phasein Vts)

Naïve average of all b s modessin2βeff = 0.52 ± 0.052.6 σ deviation betweenpenguin and tree(b s) (b c)

Naïve average of all b s modessin2βeff = 0.52 ± 0.052.6 σ deviation betweenpenguin and tree(b s) (b c)

More statistics crucial for mode-by-mode studies

32

Search for Decays with Missing Energy (Neutrinos)

33

Belle Physics Milestone

Observation of B K l+ l-

Large CP Violation in B

Observation of Large CPV and evidence of direct CPV in B π+π-

Beginning of B->φK0 saga

Direct CPV in B0 K+π−

FB asymmetry in B K* l+l-

Evidence of B τν

Observation of b dγ

# of publications= 172 as of today.

34

B τ ν Motivation

Proceed via W annihilation in the SM.

SM Branching fraction is given by

b

u W+τ +

ν

fB determination

tan cotb um mβ β+

b

u H+/W+

tanmτ β

τ +

Sensitive to the charged Higgs

35

Full Reconstruction MethodFully reconstruct one of the B’s to tag– B production– B flavor/charge– B momentum

Υ(4S)

e−(8GeV) e+(3.5GeV)

B

Bπ

full (0.1~0.3%)reconstructionB Dπ etc.

Decays of interestsB Xu l ν,B K ν νB Dτν, τν

Single B meson beam in offline !

Powerful tools for B decays w/ neutrinos

36

Signal Selection (2)Extra neutral energy in calorimeter EECL– Most powerful variable for separating signal and background– Total calorimeter energy from the neutral clusters which are not

associated with the tag B

Minimum energy thresholdBarrel : 50 MeVFor(Back)ward endcap : 100(150) MeV

Zero or small value of EECL arising only from beam background

Higher EECL due to additional neutral clusters

MC includes overlay of random trigger data to reproduce beam backgrounds.

37

Open the box !The final results are deduced by unbinned likelihood fit to the obtained EECL distributions.

Signal shape : Gauss + exponentialBackground shape : second-order polynomial

+ Gauss (peaking component)

Signal +

background

Background

B τν

Signal

Observe 17.2 events. Significance decreased to 3.5 σ

after including systematics

+5.3- 4.7

Σ : Statistical Significance

38

B τν Candidate Event

20 cm

BELLE

K+π +

π −e−

π −π +

Missing

BB++ DD0 0 ππ++

KK++ ππ-- ππ++ ππ--

BB-- τ τ -- νν

ee--νννν

39

Correction to the FPCP06 result

Error in the efficiency calculation.– Due to a coding error, the efficiency quoted in the 1st Belle

preliminary result was incorrect.

Treatment of the peaking background component.– Peaking component is subtracted for the central value.– Re-evaluate its systematic uncertainty.

The data plots and event sample are unchanged. However, fB and the branching fraction must be changed.

418.034.016.028.0 1006.1)(BF −++

−−++ ×=→ τντBPrevious

value

New value 439.056.046.049.0 10)79.1()(BF −++

−−++ ×=→ τντB (Preliminary)

40

fB Extraction

Product of B meson decay constant fB and CKM matrix element |Vub|

Using |Vub| = (4.39 ± 0.33)×10-3 from HFAG

1.6 1.1 41.4 1.3(10.1 ) 10B ubf V GeV+ + −

− −× = ×

36 3031 34229Bf M eV+ +

− −=14% = 12%(exp.) + 8%(Vub)15%

fB = 216 ± 22 MeV[HPQCD, Phys. Rev. Lett. 95, 212001 (2005) ]

41

Constraints on Charged Higgs

2σrH

A

A

B

tan / HmβB

42

Future ProspectBr(B τ ν) measurement:Further accumulation of luminosity help to reduce both statistical and systematic errors.– Some of the major systematic

errors come from limited statistics of the control sample.

|Vub| measurement:< 5% in future is an realistic goal.

fB from theory~10% now 5% ?

∆|Vub|/|Vub| = 5.8%∆fB/fB = 5%

L=5ab-1

Constraint also comes from b s γ.

43

Search for H- by B Dτν

cb

τ +H+/W+

ντ

( )tan cotb c um mβ β+

tanmτ β

( )( )

B D vBB D v

τ

µ

τµ

Γ →=

Γ →

Band width from form-factor uncertainty

Expected ∆Br ~8% @ L=5ab-1

∆(Fo

rm-fa

ctor)

~5%

∆(Form-fa

ctor) ~

15%

βtan 20 40 60

)2 M

ass

(GeV

/c±

H

100

200

300

400

500

Tevatron Run I Excluded (95% C.L.)

LEP Excluded (95% C.L.)

)-1

(140 fbντ →

Belle B

ντ→Hb, H→ t-1CMS 100fb

-1

5ab

ντ D

→B

-1 5

0ab

ντ D

→B

ντ

→tH

, H→

gb

-1

CM

S 10

0fb

βtan 20 40 60

)2 M

ass

(GeV

/c±

H

100

200

300

400

500

Constraint from B Xs γ

44

B K(*) ν ν (b s w/ two ν’s)Sensitive new physics.Theoretically very clean.Experimentally very challenging.Signature: B K(*) + nothing.Nothing may be light dark matter(see papers by Pespelov et al.).

DAMA NaI 3σ Region

CDMS 04

CDMS 05 Direct dark matter search cannot see M<10GeV region.

45

Search for K* ν ν (Belle 2006)

532M BB

Blind analysis

BELLE-CONF-0627

Sideband = 19

MC expectation = 18.7±3.3

(1.7σ stat. significance)

Yield = 4.7 +3.1-2.6

Extra Calorimeter Energy (GeV)

0 *0 4( ) 3.4 10B B K νν −→ < × (at 90% C.L)

46

Lepton Flavor ViolationQuarks have flavor mixing.

Neutrino mixing has been found.What about charged leptons ?

e µ τ

eν µν τν

? ?

(Original figure by Dr. Kuno / Osaka Univ.)

B factory is also a tau factory

47

τ lγ/3l,lητ lγ

SUSY + SeasawLarge LFV Br(τ µγ)=O(10-7~9)

( )2

32

426

2( a10 1) t nL

L

SUSY

B TeVm

mr

mτ µγ β−

⎛ ⎞⎜ ⎛ ⎞

⎜ ⎟⎝ ⎠

⎟→ ×⎜ ⎟⎝ ⎠

∼

τ 3l,lη• Neutral Higgs mediated decay.• Important when MSUSY >> EW scale.

( ) 4627 32

2

tan 10060

( 3 )

4 10A

L

L

B

Gm

r

m

meVβ

τ µ

−

→ =

⎛ ⎞⎜ ⎟× ×⎜ ⎟⎝ ⎠

⎛ ⎞⎛ ⎞⎜ ⎟⎜ ⎟

⎝ ⎠ ⎝ ⎠

( ) : ( 3 ) : ( )5 :1: 0.5

Br Br Brτ µη τ µ τ µγ→ → →=

τ ( )eµ

γ

τ0χ

( )eµ2

23(13)l(m )

τ µ

( )sµ

( )sµ

h

48

Search for τ µγ (Belle 2006)535fb-1

Tighter requirements to reduce BG.– Background x 0.28– Efficiency: 11% 6.7%– Signal region:

5σ box 2σ ellipseResults from a ML fit.– Ns = -3.9– Nb = 13.9

no signal events are found.

distribution in 2σ bandproj

ectio

n

signaldata

blinded region

preliminary

Br(τ µγ) < 4.5 x 10-8

cf.) Previous Belle;Br < 3.1 x 10-7 @ 86fb-1

49

New τ µη result from Belle401fb-1

Counting methodin 90% ellipse on Mmh-DE planeη γγ mode– eff: 6.4%– Nobserved=0 0.4 expected bkg.

η π+π-π0 mode– eff: 6.8%– Nobserved=0 0.24 expected bkg.

Upper limit w/ 2 modes

Br(τ µη)<6.5x10-890% ellipse:a region which contains 90%ofsignal MC events

preliminary

signaldata

cf.) Previous Belle;Br < 1.5 x 10-7 @ 154fb-1

50

Impact of τ µγ

MSSM + seesaw42

6

TeV160tan100.3)(

−− ⎟

⎠⎞

⎜⎝⎛×⎟

⎠⎞

⎜⎝⎛××=→ SUSYMBr βµγτ

tanβ

0

10080604020

0 1 2 3 4

Belle result

BaBar result

MSUSY (TeV/c2)

51

Impact of τ µη

427

( )

tan8.4 1060 100GeV

A

Br

M

τ µη

β −−

→

⎛ ⎞⎛ ⎞= × × ×⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠

Higgs mediated model predictsD0

CDF

Belle(90%CL)

BaBar(90%CL)

CDF• φ ττ search/310pb-1

D0• φ ττ search/325pb-1

• φ bb search/260pb-1

Belle(95%CL)

Our result has good sensitivity in comparison with Tevatron results.

52

Summary of LFV SearchCompiled by Hayasaka (Nagoya)

mode x10-7 mode x10-7

τ µγ Belle 0.45 τ lll 1.1−3.5

τ eγ BaBar 1.1 τ− µ+e−e− BaBar 1.1

τ µη Belle 0.65 τ− µ−e−e+ Belle 1.9

τ eη Belle 0.92 τ lhh BaBar 0.7−4.8

τ µη' Belle 1.3 τ− µ+π−π− BaBar 0.7

τ eη' Belle 1.6 τ lV0 Belle 2.0−7.7

τ µπ0 Belle 1.2 τ µρ0 Belle 2.0

τ eπ0 Belle 0.80 τ− Λπ− BaBar 0.59

τ µKs Belle 0.52 τ− Λπ− BaBar 0.58

τ eKs Belle 0.60 τ− ΛΚ− BaBar 0.72

τ− ΛΚ− BaBar 1.5The search region eneters into O(10-8).The search region eneters into O(10-8).

53

SummaryThe B factories both at KEK and SLAC have been so successful. The total luminosity exceeds 1ab-1 now. We are enjoying analyses.

CKM: no inconsistency found so far.

b s penguin: 2.6 σ deviation. Lower than b ccs for all 9 modes.

Missing energy decay: Belle has found the 1st evidence of B τ ν. It provides information about the charged Higgs.

LFV τ decays: search region eneters into O(10-8).

54

Cont’d

We still need a lot more luminosity.

For coming years (2007~8):– Installation of Crab cavity.– Improvement in analyses.– Cooperation with theorists.

Beyond this, we need a Super-B.The target luminosity of Super-KEKB = 8x 1035

cm-2s-1.

+ Υ(5S) run

56

Crab Cavity

59

Is the CKM Triangle Closed？50 ab-1

Yes! No!

b

d

d

b

t

t

W W0B 0B ?Something new in

60

Sensitivity to new CP phases

|ASU

SY/A

SM|2

θnew physics

Discovery region with 50 ab-1Estimated error in the measurement of time dependent CP violation

61

LFV Search at Super-B

τ ( )eµ

γ

τ0χ

( )eµ2

23(13)l(m )

τ µ

( )sµ

( )sµ

h

τ 3l, lη

τ lγ

τ3l

τl K

s

τB

γ/π

Search region enters into O(10-8 10-9)

10-9

10-8

10-7

10-6

10-5

µ− γe− γ

µ− π0

e− π0

µ− ηe− η

µ− η′e− η′

e− e+ e−

e− µ+ µ−

e+ µ− µ−

µ− e+ e−

µ+ e− e−

µ− µ+ µ−

e− π+ π−

e+ π− π−

µ− π+ π−

µ+ π− π−

e− π+ K−

e− π− K+

e+ π− K−

e− K+ K

−

e+ K− K

−

µ− π+ K−

µ− π− K+

µ+ π− K−

µ− K+ K

−

µ+ K− K

−

e− ρ0

e− KS

e− K*

e− K–*

e− φµ− ρ0

µ− KS

µ− K*

µ− K–*

µ− φ p–γ

p–π0

Λπ−

Λπ−

PDG2005 Belle BaBar

SuperKEKB10ab-1

τlγ

τlπ

/η(‘)

62

Interplay between B and τ

J.Hisano @ Tau04Workshop, Nara,Nov, 2004.J.Hisano, Y.ShimizuPLB565(2003)183.

63

CP Asymmetries in B φ Ks and b sγ

Direct asymmetry in b −> s γ

CP asymmetry in B −>φ Ks

CP asymmetry in B −> K*γ

64

B/τ Physics in the LHC Era• LHC likely/hopefully finds New Physics (NP) at

~TeV.

• If so, NP effects are likely to be seen at loops in B and τ decays.

• Such data will be useful to– Study NP flavor structure (mixing & CPV).– Identify NP scenario.

• If not, B and τ decays will be one of the best ways to find NP.

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