Tim Gershon - Centre for High Energy Physicschep.knu.ac.kr/fpcp2004/files/fpcp tim gershon.pdf · 2004-10-05 · B− → D0K− ∼ VusV∗ cb B − → D¯0K− ∼ VcsV∗ ub s

BELLE

HOT TOPICS FROM BELLE

Tim GershonIPNS, KEK

October 4, 2004

Tim Gershon FPCP 2004 October 4, 2004

BELLE Belle Collaboration


BELLE Belle Detector


BELLE Inner Detector Upgrade - Summer 2003

Number of silicon DSSDs3 layers → 4 layers

Radius of beam piper = 2.0 cm → r = 1.5 cm

Radiation hardness1 MRad → > 20 MRad

Laboratory polar angle coverage23◦ < θ < 139◦ → 17◦ < θ < 150◦

More details in K. Trabelsi’s talk

IMPROVED RESOLUTION!


BELLE KEK


BELLE Integrated Luminosity

• Approaching 300 fb−1 accumulated

• Best day: > 1 fb−1 delivered

• Results presented today use 253 fb−1 on Υ(4S)∼≡ 275 × 106 BB̄ pairs

CONTINUOUS INJECTION

∼ 30% more recordedluminosity


BELLE Some Hot Topics from Belle in 2004

• First studies of AFB in B → K∗l+l−

See talk by Y.J. Kwon

• Observation of CP violation & Evidence for direct CP violation in B → π+π−

See talk by A. Bevan

• Evidence for direct CP violation in B → K+π−

See talk by G. Graziani

• Observation of B → π0π0 and evidence for B → ρ0π0

See above talks

• Further studies of X(3872) . . . and other weird new particles See talk by S.K. Choi

• Time-Dependent CP Violation in b→ s penguin transitions? new results on B → KSKSKS & B → KSπ

0γ

See talk by M. Hazumi


BELLE CKM Phenomenology

VCKM =

Vud Vus VubVcd Vcs VcbVtd Vts Vtb

∼

1 − λ2/2 λ Aλ3(ρ− iη)

−λ 1 − λ2/2 Aλ2

Aλ3(1 − ρ− iη) −Aλ2 1

where A, λ, ρ, η are Wolfenstein parameters

From unitarity (V ∗CKMVCKM = 1):

VudV∗ub + VcdV

∗cb + VtdV

∗tb = 0

The Unitarity Triangle

φ1 ↔ β

φ2 ↔ α

φ3 ↔ γ

(0,0) (1,0)

(ρ,η)

φ1

φ2φ3

VudVub*

VcdVcb*

VtdVtb*

VcdVcb*


BELLE The Alphabet

With apologies to Z. Ligeti


BELLE φ3 from B → DK

• Can access φ3 via interference between B− → D0K− & B− → D̄0K−

• Reconstruct D in final states accessible to both D0 and D̄0

eg. DCPK− (Gronau, London, Wyler method)

• Can use multibody final states, eg. KSπ+π− (first noted by Atwood, Dunietz, Soni)

B− → D0K− ∼ VusV ∗cb B− → D̄0K− ∼ VcsV ∗

ubs

b

u

c

uW

u u

u

c

s

b

u

W

COLOUR ALLOWED COLOUR SUPPRESSED

K−)

D0K

−)

0

φφ

δ

δ3

3

(B−

DCP2A

(B−

(B−

D K−)

A

AA — amplituder = ASUPPRESSED/AFAVOURED ∼ 0.1 − 0.2

δ — strong phase difference


BELLE Principle of the Multi-Body Analysis

A. Giri, Y. Grossman, A. Soffer & J. Zupan, PRD 68, 054018 (2003)A. Poluektov et al. (Belle Collaboration), hep-ex/0406067, to appear in PRD.

• Consider D̄0 → KSπ+π−

→ define amplitude at each Dalitz plot point as f(m2+,m

2−)

where m+ = mKSπ+, m− = mKSπ

−

• Consider D0 → KSπ+π−

→ amplitude at each Dalitz plot point is f(m2−,m

2+)

•∣

∣

∣f(m2+,m

2−)

∣

∣

∣ can be measured using flavour tagged D mesons

• Consider B+ →(

KSπ+π−

)

DK+

→ amplitude is f(m2+,m

2−) + rei(δ+φ3)f(m2

−,m2+)

• Consider B− →(

KSπ+π−

)

DK−

→ amplitude is f(m2−,m

2+) + rei(δ−φ3)f(m2

+,m2−)

• Can extract (r, δ, φ3) from B+ & B− data


BELLE Illustration Using Monte Carlo

Generated 50,000 decays with r = 0.125, δ = 0, φ3 = 70◦

0

50

100

150

200

250

0 0.5 1 1.5 2 2.5 3M

2

Ksπ−, GeV

2

1

0

50

100

150

200

250

0 0.5 1 1.5 2 2.5 3M

2

Ksπ−, GeV

2

2

0

50

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200

250

300

0 0.5 1 1.5 2 2.5 3M2

Ksπ+, GeV2

3

0

50

100

150

200

250

0 0.5 1 1.5 2 2.5 3M2

Ksπ+, GeV2

4


BELLE First Results from Belle

A. Poluektov et al. (Belle Collaboration), hep-ex/0406067, to appear in PRD.

Using B± → DK± and B± → D∗K± (D∗ → Dπ0)

φ3 = 77◦ +17◦

−19◦ (stat) ± 13◦(syst) ± 11◦(model)

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

-0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4Re(reiθ)

Im(r

eiθ)

B+→D0K+

B-→D0K-

B→D0π

(a)

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

-0.6 -0.4 -0.2 0 0.2 0.4 0.6Re(reiθ)

Im(r

eiθ)

B-→D*0K-

B+→D*0K+

B→D*0π

(b)


BELLE New Results from BaBar at ICHEP2004

211 × 106BB̄ pairsB. Aubert et al. (BaBar Collaboration), BaBar-CONF-04/043, hep-ex/0408088.

Using B± → DK±, B± → D∗K± (D∗ → Dπ0) and B± → D∗K± (D∗ → Dγ)

φ3 = 88◦ ± 41◦(stat) ± 19◦(syst) ± 11◦ (model)

B± →(

KSπ+π−

)

DK± B± →

((

KSπ+π−

)

Dπ0

)

D∗K± B± →

((

KSπ+π−

)

Dγ)

D∗K±

)2

(GeV/cESm5.2 5.22 5.24 5.26 5.28

)2E

ven

ts /

( 0.

0022

5 G

eV/c

0

50

100

)2

(GeV/cESm5.2 5.22 5.24 5.26 5.28

)2E

ven

ts /

( 0.

0022

5 G

eV/c

0

50

100

BABARpreliminary

)2

(GeV/cESm5.2 5.22 5.24 5.26 5.28

)2E

ven

ts /

( 0.

0022

5 G

eV/c

0

10

20

30

40

)2

(GeV/cESm5.2 5.22 5.24 5.26 5.28

)2E

ven

ts /

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0022

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eV/c

0

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20

30

40 BABARpreliminary

)2

(GeV/cESm5.2 5.22 5.24 5.26 5.28

)2E

ven

ts /

( 0.

0022

5 G

eV/c

0

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20

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)2

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)2E

ven

ts /

( 0.

0022

5 G

eV/c

0

10

20

30 BABARpreliminary


BELLE A Comment on the Use of D∗ → Dπ0 and D∗ → Dγ

A. Bondar and T. G., hep-ph/0409281, submitted to PRD(R)

• There is an effective strong phase shift of π between the casesthat D∗ is reconstructed as D∗ → Dπ0 and D∗ → Dγ

• Arises due to CP conservation in the D∗ decay

• In the Dalitz analysis,B± →

((

KSπ+π−

)

Dπ0

)

D∗K± & B± →

((

KSπ+π−

)

Dγ

)

D∗K±

should be fitted separately (or fix the shift in δ)

• Major ramifications for ADS techniqueB± → D∗K±, D∗ → Dπ0 or D∗ → Dγ, D → K∓π±

can extract φ3 (4 ambiguities) & r using B± → D∗K± alone!

• In Belle analysis, so far we use only D∗ → Dπ0


BELLE New Today : Updated Results from Belle

HOT

• Using full data sample : 275 × 106 BB̄ pairs

• Fine tuning of D decay model

• Improved background descriptions


BELLE B± → D(∗)K± Selection

B± → DK±

0

20

40

60

80

100

-0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.2∆E (GeV)

En

trie

s/10

MeV

0

10

20

30

40

50

60

70

80

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

En

trie

s/2

MeV

276 candidate events (209 ± 16 signal)

B± → D∗K±

0

2.5

5

7.5

10

12.5

15

17.5

20

22.5

-0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.2∆E (GeV)

En

trie

s/10

MeV

0

2

4

6

8

10

12

14

16

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

En

trie

s/2

MeV

69 candidate events (58 ± 8 signal)Tim Gershon FPCP 2004 October 4, 2004

BELLE B± →(

KSπ+π−

)

DK± Dalitz Plot Distributions

M+ = f(m2+,m

2−) + rei(δ+φ3)f(m2

−,m2+)

0.5

1

1.5

2

2.5

3

0.5 1 1.5 2 2.5 3m2

+ (GeV2/c4)

m2 - (

GeV

2 /c4 )

M− = f(m2−,m

2+) + rei(δ−φ3)f(m2

+,m2−)

0.5

1

1.5

2

2.5

3

0.5 1 1.5 2 2.5 3m2

- (GeV2/c4)m

2 + (G

eV2 /c

4 )


BELLE B± →((

KSπ+π−

)

Dπ0

)

D∗0K± Dalitz Plot Distributions

M+ = f(m2+,m

2−) + rei(δ+φ3)f(m2

−,m2+)

0.5

1

1.5

2

2.5

3

0.5 1 1.5 2 2.5 3m2

+ (GeV2/c4)

m2 - (

GeV

2 /c4 )

M− = f(m2−,m

2+) + rei(δ−φ3)f(m2

+,m2−)

0.5

1

1.5

2

2.5

3

0.5 1 1.5 2 2.5 3m2

- (GeV2/c4)m

2 + (G

eV2 /c

4 )


BELLE Extraction of f(m2+,m

2−)

• Fit Dalitz plot distribution of tagged D mesons from e+e− continuum

• Tag using charge of πs in D∗+ → D0π+s

• Used model defines phase variation of f(m2+,m

2−)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 0.5 1 1.5 2 2.5 3M2 Ksπ- (GeV2/c4)

0

500

1000

1500

2000

2500

3000

3500

4000

0 0.5 1 1.5 2 2.5 3M2 π+π- (GeV2/c4)

0

250

500

750

1000

1250

1500

1750

2000

0 0.5 1 1.5 2 2.5 3M2 Ksπ+ (GeV2/c4)

χ2/ndf = 2.30

(ndf = 1106)

Fine tuning of model little effect on φ3


BELLE Measurement of f(m2+,m

2−) - Results

Resonance Amplitude Phase (◦) FractionKSσ1 1.57 ± 0.10 214 ± 4 9.8%

BW → GS → KSρ0 1.0 (fixed) 0 (fixed) 21.6%

KSω 0.0310 ± 0.0010 113.4 ± 1.9 0.4%KSf0(980) 0.394 ± 0.006 207 ± 3 4.9%KSσ2 0.23 ± 0.03 210 ± 13 0.6%KSf2(1270) 1.32 ± 0.04 348 ± 2 1.5%

UPDATED → KSf0(1370) 1.25 ± 0.10 69 ± 8 1.1%NEW; GS → KSρ

0(1450) 0.89 ± 0.07 1 ± 6 0.4%K∗(892)+π− 1.621 ± 0.010 131.7 ± 0.5 61.2%K∗(892)−π+ 0.154 ± 0.005 317.7 ± 1.6 0.55%

NEW → K∗(1410)+π− 0.22 ± 0.04 120 ± 14 0.05%NEW → K∗(1410)−π+ 0.35 ± 0.04 253 ± 6 0.14%

K∗0(1430)

+π− 2.15 ± 0.04 348.7 ± 1.1 7.4%K∗

0(1430)−π+ 0.52 ± 0.04 89 ± 4 0.43%

K∗2(1430)

+π− 1.11 ± 0.03 320.5 ± 1.8 2.2%K∗

2(1430)−π+ 0.23 ± 0.02 263 ± 7 0.09%

K∗(1680)+π− 2.34 ± 0.26 110 ± 5 0.36%K∗(1680)−π+ 1.3 ± 0.2 87 ± 11 0.11%nonresonant 3.8 ± 0.3 157 ± 4 9.7%


BELLE Test Samples

Fit B, B̄ samples separately, float r±eiθ±, where θ± = δ ± φ3

B± →(

KSπ+π−

)

Dπ±

(r ∼ 0.01)

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

-0.15 -0.1 -0.05 0 0.05 0.1 0.15Re(r eiθ)

Im(r

eiθ)

B+

B-

3425 events

r− = 0.047 ± 0.018

θ− = 193◦ ± 24◦

r+ = 0.039 ± 0.021

θ− = 240◦ ± 28◦

B± →((

KSπ+π−

)

Dπ0

)

D∗π±

(r ∼ 0.01)

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

-0.3 -0.2 -0.1 0 0.1 0.2 0.3Re(r eiθ)

Im(r

eiθ)

B+

B-

641 events

r− = 0.086 ± 0.049

θ− = 280◦ ± 30◦

r+ = 0.015 ± 0.042

θ− = 170◦ ± 186◦


BELLE Fits to Extract φ3

Fit B± samples separately, float rei(δ±φ3)

B± →(

KSπ+π−

)

DK±


-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

-0.4-0.3-0.2-0.1 0 0.1 0.2 0.3 0.4Re(r eiθ)

Im(r

eiθ)

B+→DK+

B-→DK-

B± →((

KSπ+π−

)

Dπ0

)

D∗K±


-0.6

-0.4

-0.2

0

0.2

0.4

0.6

-0.6 -0.4 -0.2 0 0.2 0.4 0.6Re(r eiθ)

Im(r

eiθ)

B-→D*K-

B+→D*K+

PRELIMINARY Results from simultaneous fits (B+ & B−) (Errors from likelihood curves)

? r = 0.247 ± 0.071? φ3 = 63.7◦ ± 15.2◦

? δ = 156.6◦ ± 15.6◦

? r = 0.254 ± 0.116? φ3 = 74.9◦ ± 25.2◦

? δ = 321.3◦ ± 25.0◦


BELLE Systematic Errors

B± → DK± B± → D∗K±

Source ∆r ∆φ3 ∆δ ∆r ∆φ3 ∆δBackground shape 0.027 5.7◦ 4.1◦ 0.014 3.1◦ 5.3◦

Background fraction 0.006 0.2◦ 1.0◦ 0.005 0.7◦ 1.4◦

Efficiency shape 0.012 4.9◦ 2.4◦ 0.002 3.5◦ 1.0◦

Momentum resolution 0.002 0.3◦ 0.3◦ 0.002 1.7◦ 1.4◦

Control sample bias 0.004 10.2◦ 10.2◦ 0.004 9.9◦ 9.9◦

Total 0.030 12.7◦ 11.3◦ 0.016 11.1◦ 11.4◦


BELLE Model Uncertainty

f(m2+,m

2−) =

∣

∣

∣f(m2+,m

2−)

∣

∣

∣ eiφ(m2

+,m2−)

• Fit to flavour tagged D sample measures∣

∣

∣f(m2+,m

2−)

∣

∣

∣

BUT φ(m2+,m

2−) model-dependent

• Estimate model uncertainty by varying model

Fit model (∆r)max (∆φ3)max (∆δ)max

Meson formfactors Fr = FD = 1 0.01 3.1◦ 3.3◦

Constant BW width Γ(q2) 0.02 4.7◦ 9.0◦

Only K∗, ρ, ω, f0 non-resonant 0.03 9.9◦ 18.2◦

Total 0.04 11◦ 21◦

• Consider CP -tagged D mesons decaying to KSπ+π−

→ amplitude is f(m2+,m

2−) ± f(m2

−,m2+)

• FUTURE: use CP tagged D mesons from cτ factory (ψ′′ → DD̄)↪→ measure φ(m2

+,m2−) ⇒ remove model uncertainty


BELLE Extraction of φ3: B± →(

KSπ+π−

)

DK±

Avoid using fit likelihood errors → use frequentist approach to obtain confidence regions

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 50 100 150 200 250 300 350

20%

74%

97%

φ3 (deg)

r

0

50

100

150

200

250

300

350

0 50 100 150 200 250 300 350

20%

74%

97%

φ3 (deg)

δ (d

eg)

B± →(

KSπ+π−

)

DK±: PRELIMINARY

φ3 = 64◦ ± 19◦(stat) ± 13◦(syst) ± 11◦(model)r = 0.21 ± 0.08(stat) ± 0.03(syst) ± 0.04(model)δ = 157◦ ± 19◦(stat) ± 11◦(syst) ± 21◦(model)

r > 0 @ 99.3% CLCPV @ 94% CL


BELLE Extraction of φ3: B± →((

KSπ+π−

)

Dπ0

)

D∗K±

Avoid using fit likelihood errors → use frequentist approach to obtain confidence regions

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 50 100 150 200 250 300 350

20%

74%

97%

φ3 (deg)

r

0

50

100

150

200

250

300

350

0 50 100 150 200 250 300 350

20%

20%

φ3 (deg)

δ (d

eg)

B± →((

KSπ+π−

)

Dπ0

)

D∗K±: PRELIMINARY

φ3 = 75◦ ± 57◦(stat) ± 11◦(syst) ± 11◦(model)

r = 0.12+0.16−0.11(stat) ± 0.02(syst) ± 0.04(model)

δ = 321◦ ± 57◦(stat) ± 11◦(syst) ± 21◦(model)

r > 0 @ 56% CLCPV @ 38% CL


BELLE Extraction of φ3: Combined Modes

Use frequentist approach with Feldman-Cousins ordering to obtain confidence regions

φ3 = 68◦ +14◦

−15◦ (stat) ± 13◦(syst) ± 11◦(model)

r(B± → DK±) = 0.21 ± 0.08(stat) ± 0.03(syst) ± 0.04(model)

CPV @ 98% CL

Two standard deviation interval including systematic and model uncertainties:22◦ < φ3 < 113◦

Compare to previous results:

Belle (152 × 106BB̄) BaBar (211 × 106BB̄)φ3 = 77◦ +17◦

−19◦ (stat) ± 13◦(syst) ± 11◦(model) φ3 = 88◦ ± 41◦(stat) ± 19◦(syst) ± 11◦(model)

NB statistical error depends on value of r

r(B± → DK±) = 0.26 +0.10−0.14 ± 0.03 ± 0.04 r(B± → DK±) < 0.18


BELLE Slight Digression on r

Various analyses in the B± → D(∗)K± system provide information about rNaive expectation: r ∼ 0.1 − 0.2

r(B± → DK±)

Dalitz ADSB± →

(

KSπ+π−

)

DK± B± →

(

K∓π±)

DK±

Belle r = 0.21 ± 0.08 ± 0.03 ± 0.04 (∗) r < 0.28

BaBar r < 0.18 r < 0.23

(∗) r > 0 @ 99.3% CL (stat)

r(B± → D∗K±)

Dalitz ADSB± →

(

( )D π0)

D∗K± B± → (( )D γ)D∗ K± B± →

(

( )D π0)

D∗K± B± → (( )D γ)D∗ K±

Belle r = 0.12+0.16−0.11 ± 0.02 ± 0.04

BaBar r < 0.24 r < 0.21

hep-ph/0409281 possible bias r < 0.13

No serious disagreement with current statistical precision


BELLE Summary

• Many hot topics from Belle . . . I have discussed only one

• Most precise measurement of φ3

φ3 = 68◦ +14◦

−15◦ (stat) ± 13◦(syst) ± 11◦(model)

• Hint of CP violation at 98% CL

• Two standard deviation interval: 22◦ < φ3 < 113◦

• More new results from Belle still to come in this conference!


BELLE Back-Up Slides

BACK UP


BELLE Comparison of SVD1 data and SVD2 data

Comparison for B± → DK±

SVD1: 152 × 106BB̄ pairs

-0.4

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-0.2

-0.1

0

0.1

0.2

0.3

0.4

-0.4-0.3-0.2-0.1 0 0.1 0.2 0.3 0.4Re(r eiθ)

Im(r

eiθ)

B+->D0K+

B-->D0K-

SVD2: 123 × 106BB̄ pairs

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

-0.4-0.3-0.2-0.1 0 0.1 0.2 0.3 0.4Re(r eiθ)

Im(r

eiθ)

B+→DK+

B-→DK-

(Errors from likelihood curves)

? r = 0.31 ± 0.11? φ3 = 86◦ ± 17◦

? δ = 168◦ ± 17◦

? r = 0.32 ± 0.10? φ3 = 51◦ ± 18◦

? δ = 158◦ ± 18◦


BELLE Dependence of φ3 Error on r

Nice picture from BaBar!

Br0 0.05 0.1 0.15 0.2 0.25 0.3

) de

gree

γ(σ

0

10

20

30

40

50

60

70

BABARpreliminary


BELLE Background Treatment

We consider the following sources of background, for B± → DK± :

? Random combinations & real D plus random kaon 21%background level from ∆E distributionstudy Dalitz distribution using data with reversed continuum suppression

∗ BB̄ events 2.3%study using generic Monte Carlo

∗ B± → DK± with misreconstructed D 0.3%study with signal Monte Carlo

∗ B± → DK± with misreconstructed K < 0.4% @ 95% CLstudy with signal Monte Carlo

∗ B± → Dπ± 0.9%background level from ∆E distributionDalitz shape is known


Documents

Tim Gershon - Centre for High Energy Physicschep.knu.ac.kr/fpcp2004/files/fpcp tim gershon.pdf · 2004-10-05 · B− → D0K− ∼ VusV∗ cb B − → D¯0K− ∼ VcsV∗ ub s