Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0...

43
Oct 14, 2003; Pittsburgh, PA Takeo Higuchi, KEK BEAUTY2003 Takeo Higuchi Institute of Particle and Nuclear Studies, KEK for the Belle collaboration Hot Topics from the Belle Experiment Hot Topics from the Belle Experiment

Transcript of Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0...

Page 1: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Oct 14, 2003;Pittsburgh, PA

Takeo Higuchi, KEKBEAUTY2003

Takeo HiguchiInstitute of Particle and Nuclear Studies, KEK

for the Belle collaboration

Hot Topicsfrom the Belle Exper iment

Hot Topicsfrom the Belle Exper iment

Page 2: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

• Introduction to the Belle exper iment

• CP violation in B0 →→→→ φφφφKS

• Evidence of B0 →→→→ ππππ 0ππππ 0

• New resonance X(3872)• Summary

ContentsContents

Page 3: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Introduction to the Belle Exper iment

Introduction to the Belle Exper iment

Page 4: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

e+e−

3km circumferenceL = (1.06 ×××× 1034)/cm2/sec���� L dt = 158 fb−−−−1

On-resonance 140 fb−−−−1

L = (1.06 ×××× 1034)/cm2/sec���� L dt = 158 fb−−−−1

On-resonance 140 fb−−−−1

World Records

HistoryHistory

1999 Jun 2003 Jul

• 3.5 GeV e+ ×××× 8.0 GeV e−

– e+e− → ϒ(4S) with βγ = 0.425.

– Crossing angle = ±11 mrad.

KEKB Accelerator KEKB Accelerator

Page 5: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Belle DetectorBelle Detector

KL µµµµ detector14/15 layer RPC+Fe

Electromagnetic Calor imeterCsI(Tl) 16X0

Aerogel Cherenkov Countern = 1.015~1.030

Si Vertex Detector3 layer DSSD

TOF counter

8.0 GeV e−−−−

3.5 GeV e+

Central Dr ift ChamberTracking + dE/dx50-layers + He/C2H5

Page 6: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

PeoplePeople

274 authors, 45 institutionsmany nations

274 274 authors, 45 institutionsauthors, 45 institutionsmany nationsmany nations

Page 7: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

CP Violation in B0 →→→→ φφφφKSCP Violation in B0 →→→→ φφφφKS

Page 8: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

CP Violation by Kobayashi-MaskawaCP Violation by Kobayashi-Maskawa

���

���

1−−−−1−

−−1=���

���

3

2

32

2

2

)1(

2/

)(2/

ληρλλλλ

ηρλλλ

AiA

A

iA

VVV

VVV

VVV

tbtstd

cbcscd

ubusud

KM ansatz: CP violation is due tocomplex phase in quark mixing matrix

KM ansatz: CP violation is due tocomplex phase in quark mixing matrix

unitarity triangle

CP violation parameters(φ1, φ2, φ3) = (β, α, γ)

CP violation parameters(φ1, φ2, φ3) = (β, α, γ)

O ρ

η

Page 9: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Time-Dependent CP AsymmetryTime-Dependent CP Asymmetry

0 0

0 0

0 0

( ) ( )( ) sin cos

( ) ( )

d CP d CPB B

d CP d CP

B f B fA t m At m

B f fS t

B

Γ → − Γ →= = − ⋅ ∆ + ⋅ ∆Γ → + Γ →

Inputs: ξf = −1, S = 0.6A = 0.0

0d CPB f→0

d CPB f→

2

2 2

: eigenvalue

2Im( ) | | 1,

| | 1 | | 1

f

AS

CPξ

λ λλ λ

−= =+ +

A = 0 or |λ| = 1 → No direct CPV

S = −ξfsin2φ1: SM prediction

Page 10: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

New Physics Hunting in b →→→→ sqqNew Physics Hunting in b →→→→ sqq

b

d

s

d

s

s

φ

Ks

B0

W

gt

d d

s

s Ks

η’

B0 g

g~b s

+(δ 23

dRR)b~R

s~R

φ+

New process w/ different CP phase

New process w/ different CP phaseSM penguinSM penguin

Deviation from b →→→→ ccs Hint of new physics

SM predicts same CPV in b →→→→ ccs and sqq.

SM predicts same CPV in b →→→→ ccs and sqq.

e.g.) squark penguin

New physics may deviate CPV in b →→→→ ccs from sqqNew physics may deviate CPV in b →→→→ ccs from sqq

Page 11: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

b →→→→ ccs Reconstructionb →→→→ ccs Reconstruction

5417 events are used in the fit.

140 fb−1, 152M BB pairs

J/ψ KL signal

B 0 →→→→ J/ψψψψKL

b →→→→ ccs w/o J/ψψψψKL

pB* (cms)

Beam-energy constrained mass (GeV/c2)

Detail by K.MiyabayashiDetail by K.Miyabayashi

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CP Violation in b →→→→ ccsCP Violation in b →→→→ ccs

5417 events @ 152M BB

1sin2

0.733 0.057 0.028

φ =± ±

1.007 0.041 (stat)ccsλ = ±consistent with no direct CPV

poor flavor tag

fine flavor tag

Small systematic uncertainty↓

Well controlled analysis technique

Small systematic uncertainty↓

Well controlled analysis technique

Detail by K.MiyabayashiDetail by K.Miyabayashi

K. Abe et al. [Belle collaboration], BELLE-CONF-0353.

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b →→→→ sqq Reconstructionsb →→→→ sqq Reconstructions

• B0 →→→→ φφφφKS: φφφφ →→→→K+K−−−−, KS →→→→ ππππ++++ππππ−−−−

– Minimal kaon-identification requirements.– Belle standard KS selection.– | M(KK) − M(φ) | < 10MeV/c2

(mass resolution = 3.6 MeV/c2).– | pφ | in CMS > 2.0 GeV/c.– Belle standard continuum suppression (given later.)– | ∆E | < 60MeV, 5.27 < Mbc < 5.29 GeV/c2. M(KK) [GeV/c2]

• Background is dominated by continuum• CP in the background:

– K+K−KS: (7.2±1.7)%– f 0(980)KS:– These effects are included in the systematic error.

• Background is dominated by continuum• CP in the background:

– K+K−KS: (7.2±1.7)%– f 0(980)KS:– These effects are included in the systematic error.

1.91.5(1.6 )%+

Page 14: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

b →→→→ sqq Reconstructions −−−− Cont’db →→→→ sqq Reconstructions −−−− Cont’d

• B0 →→→→ ΚΚΚΚ++++ΚΚΚΚ−−−−KS– More stringent kaon-identification requirements.– Particle veto for φ, D0, χc0, and J/ψ → K+K− and D+ → K+KS.– Belle standard continuum suppression.– | ∆E | < 40 MeV, 5.27 < Mbc < 5.29 GeV/c2.

• B0 →→→→ ηηηη´KS: 1) ηηηη´ →→→→ ργργργργ, ρρρρ →→→→ ππππ+ππππ−−−−

2) ηηηη´ →→→→ ηπηπηπηπ+ππππ−−−−, ηηηη →→→→ γγγγγγγγ– Belle standard continuum suppression.– |∆E| < 60MeV (η´ → ργ); −100 < ∆E < +80 MeV (η´ → ηπ+π−)

5.27 < Mbc < 5.29 GeV/c2

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0

10

20

30

5.2 5.22 5.24 5.26 5.28 5.3

a) B0 → φK0s

0

50

100

5.2 5.22 5.24 5.26 5.28 5.3

b) B0 → K+K−K0s

Ent

ries

/ 0.0

025

GeV

/c2

0

50

100

150

5.2 5.22 5.24 5.26 5.28 5.3Mbc (GeV/c2)Mbc (GeV/c2)Mbc (GeV/c2)

c) B0 → η’K0s

B0 →→→→ φφφφKS

B0 →→→→ K++++K−−−−KS

B0 →→→→ ηηηη′′′′KS

2 cms 2 cms 2bc beam(GeV/ ) ( ) ( )BM c E p≡ −

Beam-Energy Constrained MassBeam-Energy Constrained Mass

68±11 signals106 candidates for Sand A fitpurity = 0.64±0.10efficiency = 27.3%

244±21 signals421 candidates for Sand A fitpurity = 0.58±0.05efficiency = 17.7% (η´→ ηπ+π−)

15.7% (η´→ ργ )

199±18 signals361 candidates for Sand A fitpurity = 0.55±0.05efficiency = 15.7%

Page 16: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Unbinned Maximum Likelihood FitUnbinned Maximum Likelihood Fit

1. fsig: Event by event signal probability

( )0 01 (1 2 ) sin( ) cos( )4

Bt

B BB

eq w m t m tS A

τ

τ

− ∆− − ∆ ∆ + ∆ ∆2. �sig:

3. R: ∆t resolution function

4. Pbkg: Background ∆t distribution

signal background

cand 2maximize

1

( , ) ( ; , ) 0N

ii

LL PA A

AtS S

S=

∂= ∆ → =∂ ∂∏

sig sig sig bkg( ; , ) P ( ; , ) (1 ) ( )i S SP t f t f P tA A R∆ = ⋅ ∆ ⊗ + − ⋅ ∆

Page 17: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

CP Violation in b →→→→ sqqCP Violation in b →→→→ sqq

-1

-0.5

0

0.5

1

-7.5 -5 -2.5 0 2.5 5 7.5

Raw

Asy

mm

etry

0.0 < r ≤ 0.5

f) B0 → η’K0s

-1

-0.5

0

0.5

1

-7.5 -5 -2.5 0 2.5 5 7.5∆t (ps)∆t (ps)∆t (ps)

0.5 < r ≤ 1.0

g)

-1

-0.5

0

0.5

1

-7.5 -5 -2.5 0 2.5 5 7.5

Raw

Asy

mm

etry

0.0 < r ≤ 0.5

d) B0 → K+K−K0s

-1

-0.5

0

0.5

1

-7.5 -5 -2.5 0 2.5 5 7.5∆t (ps)∆t (ps)∆t (ps)

0.5 < r ≤ 1.0

e)

-1

-0.5

0

0.5

1

-7.5 -5 -2.5 0 2.5 5 7.5

Raw

Asy

mm

etry

0.0 < r ≤ 0.5

b) B0 → φK0s

-1

-0.5

0

0.5

1

-7.5 -5 -2.5 0 2.5 5 7.5∆t (ps)∆t (ps)∆t (ps)

0.5 < r ≤ 1.0

c)

B0 →→→→ φφφφKS B0 →→→→ K+K−KS B0 →→→→ ηηηη’KS

A

−−−−ξξξξfS09.011.050.096.0 +

−±−

07.029.015.0 ±±−

18.000.005.026.051.0 +

−±±+

04.016.017.0 ±±−

05.027.043.0 ±±+

04.016.001.0 ±±−

B → fCP(sqq) decay vertices are reconstructed using K- or π-track pair.

Fitsin2φφφφ1@ 152M BB

Page 18: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Consistency ChecksConsistency Checks

• CP violation parameters with A = 0– B0 → φKS: −ξfS = −0.99 ± 0.50

– B0 → K+K−KS: −ξfS= +0.54 ± 0.24

– B0 → η′KS: −ξfS= +0.43 ± 0.27

• Null asymmetry tests for S term– B+ → φK+: −ξfS= −0.09 ± 0.26

– B+ → η′K+: −ξfS= +0.10 ± 0.14

Less correlationbtw Sand A

Less correlationbtw Sand A

26.009.0 ±−=S

Consistent with S = 0Consistent with S = 0

Page 19: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Statistical SignificanceStatistical Significance

0

2

4

6

8

10

12

14

16

-2 -1.5 -1 -0.5 0 0.5 1

-2ln

(L/L

max

)

S(φK0s)

a)

sin2φ1

Hint of new physics?Need more data to establish conclusion.

Hint of new physics?Need more data to establish conclusion.

• B0 →→→→ K++++K−−−−KS, ηηηη KS

– Consistent with sin2φ1.

• B0 →→→→ φφφφKS

– 3.5σσσσ deviation (Feldman-Cousins).

– S(φKS) = sin2φ1: 0.05% probability.

0( )SS Kφ

K. Abe et al. [Belle collaboration], hep-ex/0308035, submitted to Phys. Rev. Lett.

Page 20: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Evidence of B0 →→→→ ππππ0ππππ0Evidence of B0 →→→→ ππππ0ππππ0

Page 21: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Two possible diagrams require measured φφφφ2 disentangledTwo possible diagrams require measured φφφφ2 disentangled

Disentangling φφφφ2Disentangling φφφφ2

b u

d

u

W

W

d

u

u

bt

B0 →→→→ ππππ ++++ππππ −−−− is one of promising decays to measure φφφφ2B0 →→→→ ππππ ++++ππππ −−−− is one of promising decays to measure φφφφ2

TT PP

22, 1 sin2( )A S Aππ ππ ππ φ θ= − +

Penguin-polluted CP violation

Br(B0 →→→→ ππππ 0ππππ 0) measurement gives constraint on θθθθ.

eff2φ

Page 22: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

B0 →→→→ ππππ0ππππ0 ReconstructionB0 →→→→ ππππ0ππππ0 Reconstruction

• B0 reconstruction– 2 π 0’s with 115 < M(γγ) < 152 MeV/c2.

– Efficiency = 9.90 ± 0.03%.

– Those MC-determined distributions are used in extraction of signal yield with calibration using B+ → D0π+ decays in data.

Signal MC Signal MC

∆E [GeV]Mbc [GeV/c2]

Page 23: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Continuum SuppressionContinuum Suppression

Fisher

|cosθB|

|r|

Multi-dimensionallikelihood ratio

Continuum

Signal MC

e+e− → BB e+e− → qq

• 1−cos2θ for BB

• flat for qq

Construct likelihood

• r = high → well tagged→ originated from B decay

• r = low → poorly tagged→ originated from qq

Flavor tag quality

B flight direction

Fisher

sig

sig

MDLH 0.95qq

L

L L≡ >

+

Page 24: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

B++++ →→→→ ρρρρ++++ππππ0 ContaminationB++++ →→→→ ρρρρ++++ππππ0 Contamination

• ∆E-Mbc shape: MC-determined 2-dimensional distribution.

• Yield: Recent Br measurement with MC-determined efficiency.

According to MC study, other charmless decays than B+ → ρ+π0 are negligible.

According to MC study, other charmless decays than B+ → ρ+π0 are negligible.

Br(B+ → ρ+π0) measurement: B. Aubert et al. [BaBar collaboration], hep-ex/0307087, submitted to PRL.

B+ → ρ+π0

π+π0

B+ → ρ+π0

∆E [GeV] Mbc [GeV/c2]

charmless background incl. ρ+π0

Page 25: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Signal ExtractionSignal Extraction

Mbc [GeV/c2] ∆E [GeV]

@ 152 M BB

B++++ →→→→ ρρρρ++++π π π π 0 (modeled by MC)

Signal

Continuum

Signal yield: Signal yield: 9.78.425.6SN +

−=Unbinned maximum likelihood fit

Branching fractionBranching fraction0 0 0

6

( )

(1.7 0.6 0.2) 10

Br B π π−

= ± ± ×

Signal shape is modeled by MC, and is calibrated using B+ → D0π+ decays in data.

Significance incl. systematic er ror = 3.4σσσσS.H.Lee, K.Suzuki et al. [Belle collaboration], hep-ex/0308040, submitted to Phys. Rev. Lett.

Page 26: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

New Resonance X(3872)New Resonance X(3872)

Page 27: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

New Narrow Resonance: X →→→→ ππππ++++ππππ−−−−J/ψψψψNew Narrow Resonance: X →→→→ ππππ++++ππππ−−−−J/ψψψψ

• Mass distr ibution:

Data MC

( / ) ( / )M J M Jπ π ψ ψ+ − −

ψψψψ(2S) ψψψψ(2S)

X

New resonance X is found.

[GeV/c2][GeV/c2]

Eve

nts

/ 0.0

10 G

eV/c

2

• γ conversion elimination

2

( ) ( / )

20MeV/

M M J

c

ψ+ − −

<

� �

2( ) 400MeV/M cπ π+ − >

Page 28: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

B+ →→→→ K+XB+ →→→→ K+X

• B+ →→→→ K+X reconstruction– Add loosely identified kaon to X.

5.20 5.25 5.30 3.84 3.88 3.92 0.0 0.2[GeV/c2] [GeV/c2] [GeV]

Mbc MππJ/ψ ∆E

3-dim. unbinnedlikelihood fit.3-dim. unbinnedlikelihood fit.

meas meas PDG 2(2 ) (2 ) 3872.0 0.6 0.5 MeV/X X S SM M M M cψ ψ= − + = ± ±

2

( / )2.3 MeV/

M Jc

π π ψ+ −Γ <

sig 35.7 6.8N = ±

( ) ( / )0.063 0.012 0.007

( (2 )) ( (2 ) / )

Br B K X Br X J

Br B K S Br S J

π π ψψ ψ π π ψ

+ + + −

+ + + −→ × → = ± ±

→ × →

@ 152M BB

Page 29: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

What is X?What is X?

• Hypothesis I : 13D2

– M(X) = 3872 MeV/c2 differs fromprediction: M(13D2) = 3810 MeV/c2.

– Γ(13D2 → γχc1)/Γ(13D2 → ππJ/ψ) ~ 5,while Γ(X → γχc1)/Γ(X → ππJ/ψ) < 1

Mbc

M(γχc1)

No clear signal

1( ) / ( / ) 0.89 @ 90% CLcX X Jγχ ππ ψΓ → Γ → <

E.Eichten et al., Phys. Rev. D21, 203 (1980);W.Buchmüller and S.-H.H.Tye, Phys. Rev. D24, 132 (1981).

Page 30: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

What is X? −−−− Cont’dWhat is X? −−−− Cont’d

• Hypothesis I I : “ molecular” charmonium– M(X) = 3872 ± 0.6 ± 0.5 MeV.

– M(D0) + M(D0*) = 3871.2 ± 1.0 MeV.

– Do above facts suggest loosely bound D0-D0* state?

– Need more data to conclude.

QQ q q D0-D0* “molecule”

S.-K.Choi, S.L.Olsen et al. [Belle collaboration], hep-ex/0309032, submitted to Phys. Rev. Lett.

Page 31: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

SummarySummary

Page 32: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

SummarySummary

• 3.5σ deviation is observed with Feldman-Cousins in CP violation in B0 → φKS from the SM.� Hint of new physics?

• Br(B0 → π 0π 0) = (1.7±0.6±0.2)×106 is measured, which gives constraint on penguin uncertainty in φ2.

• New resonance of X → π+π−J/ψ is observed at M(X) = 3872.0±0.6±0.5 MeV/c2 that does not look like ccstate.

Page 33: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Backup SlidesBackup Slides

Page 34: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Mixing-Induced CP ViolationMixing-Induced CP Violation

B0

B0 B0

VtbV*

V*Vtb

φφφφ

KS++++td

td

Sanda, Bigi & Car ter

1

2

2

( )td

i

V

e φ

∝b

d

b

d

t

t

W W

b

d

φφφφ

KS

W

W

t

tg

g

d

s

s

s

d

s

s

s

Vtb Vts

Vtb Vts

Page 35: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

How to Measure CP Violation?How to Measure CP Violation?

• Find B fCP decay• Identify (= “ tag” ) flavor of B fCP

• Measure decay-time difference: ∆∆∆∆t• Determine asymmetry in ∆∆∆∆t distr ibutions

e−−−− e+e−−−−: 8.0 GeVe++++: 3.5 GeV

BCP

∆∆∆∆z

Btag

ϒϒϒϒ(4S)βγβγβγβγ ~ 0.425

fCPfCP

( )

z

ct

βγ ϒ

∆ ∆�

∆∆∆∆z cβγτβγτβγτβγτB ~ 200 µµµµm

flavor tagflavor tag

Detail by K.MiyabayashiDetail by K.Miyabayashi

Page 36: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Systematic Error of CPV in b →→→→ ccsSystematic Error of CPV in b →→→→ ccs

< 0.005∆t background distribution

< 0.005∆mB, τB

0.028Total

0.008Btag decay interference

0.008Fit bias

0.008∆t resolution function

0.007Signal fraction (other)

0.012Signal fraction (J/ψKL)

0.013Vertex reconstruction

0.014Flavor tag

ErrorSources

Small uncer tainty inanalysis procedure

Small uncer tainty inanalysis procedure

stat err. = 0.057

Page 37: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

B0 →→→→ K++++K−−−−KS: CP = ±±±±1 MixtureB0 →→→→ K++++K−−−−KS: CP = ±±±±1 Mixture

K-

KSB0

J=0 J=0J=0

J=0

�������� CP = (−−−−1)����CP = (−−−−1)����

decay

CP = +1 CP = +1

K+

CP = ±±±±1 fraction is equal to that of ���� =even/oddCP = ±±±±1 fraction is equal to that of ���� =even/odd

Since B0 → K+K−KS is 3-body decay,the final state is a mixture of CP = ±1.

How can we determine the mixing fraction?

Page 38: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

�-even fraction in |K0K0> can be determined by |KSKS> system

��

Using isospin symmetry,

CP evenCP even%015

100+−

B0 →→→→ K++++K−−−−KS: CP = ±±±±1 Mixture −−−− Cont’dB0 →→→→ K++++K−−−−KS: CP = ±±±±1 Mixture −−−− Cont’d

Page 39: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

∆∆∆∆t Distr ibutions∆∆∆∆t Distr ibutions

∆t [ps] ∆t [ps]∆t [ps]

B0 →→→→ φφφφKSB0 →→→→ φφφφKS B0 →→→→ K+K−KSB0 →→→→ K+K−KS B0 →→→→ ηηηη’KSB0 →→→→ ηηηη’KS

qξf = −1

qξf = +1

qξf = −1

qξf = +1

qξf = −1

qξf = +1

Page 40: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Systematic Errors of CPV in b →→→→ sqqSystematic Errors of CPV in b →→→→ sqq

S A S A S AWtag fractions

�� ��

0.018

�� ��

0.007

�� ��

0.005�� ��

0.006

�� ��

0.005

�� ��

0.007Physics parameters

�� ��

0.033

�� ��

0.002

�� ��

0.006�� ��

0.002

�� ��

0.003

�� ��

0.003Ver texing

�� ��

0.022

�� ��

0.046

�� ��

0.016�� ��

0.027

�� ��

0.044

�� ��

0.024Background fraction

�� ��

0.053

�� ��

0.035�� ��

0.045

�� ��

0.026

�� ��

0.029

�� ��

0.036Background ∆∆∆∆t

�� ��

0.015

�� ��

0.008�� ��

0.003

�� ��

0.003

�� ��

0.010

�� ��

0.006Resolution function

�� ��

0.013

�� ��

0.005�� ��

0.004

�� ��

0.003

�� ��

0.007

�� ��

0.004KKKs + f0Ks bkg. +0.001

�� ��

0.039-0.084

Sum +0.09 0.07 0.05 0.04 0.05 0.04-0.11

φφφφKS ηηηη'KS KKKS

Systematics are small and well understood from b → ccs studies.

Page 41: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Systematic Uncer taintySystematic Uncer tainty

+2.0%−2.0%MDLR selection

++++Eff−−−−EffSources

++++3.43−−−−3.34Total

−−−−9.09.09.09.0%

−0.5%

−7.0%

−5.3%

−0.99

−0.69

−0.04

−0.62

−0.03

−−−−∆∆∆∆NS

+0.5%Luminosity

++++9.5%Total

+7.0%π0 efficiency

+6.1%Fitting

+1.33Rare B (ρ+π0)

+0.67Mbc width

+0.04Mbc peak position

+0.45∆E width

+0.04∆E peak position

++++∆∆∆∆NSSources

Page 42: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

M(ππππ++++ππππ−−−−) Distr ibutionM(ππππ++++ππππ−−−−) Distr ibution

M(π+π−) [GeV/c2]

Fit to ρρρρ-mass is pretty good

– M(π+π−) can be fitted by ρ-mass distribution well.

– 13D2 → ρJ/ψ is forbidden by isospin conservation rule.

Page 43: Hot Topics from the Belle Experiment14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 3 layer DSSD TOF counter

Constraint on θθθθConstraint on θθθθ

0 0A A+ −= �

00A

1

2A+−

1

2A+−�

00A�2θ

Amp(B0 → π0π0)

Amp(B0 → π0π0)

Amp(B− → π−π0)

Amp(B+ → π+π0)

Amp(B0 → π+π−)

Amp(B0 → π+π−)

A+−�

A+−

0A−�

0A+

00A�

00A

0 00 2 012

0 2

( )cos2

1

B B B B B

B B Aππ

θ+− + +− +

+− +

+ + −≥

( )ij i jB Br B π π≡ →

• B++++0/B++++−−−− = 1.04• B00/B++++−−−− = 0.39• Aππππππππ = 0.57

Using Our Results

eff2 2| | | | 44.0 (90%C.L.)θ φ φ= − < �

Belle PreliminaryBelle Preliminary

M.Gronau et al., Phys. Lett. B 514, 315 (2001).