Tim Gershon - Centre for High Energy Physicschep.knu.ac.kr/fpcp2004/files/fpcp tim gershon.pdf ·...
Transcript of Tim Gershon - Centre for High Energy Physicschep.knu.ac.kr/fpcp2004/files/fpcp tim gershon.pdf ·...
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BELLE
HOT TOPICS FROM BELLE
Tim GershonIPNS, KEK
October 4, 2004
Tim Gershon FPCP 2004 October 4, 2004
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BELLE Belle Collaboration
Tim Gershon FPCP 2004 October 4, 2004
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BELLE Belle Detector
Tim Gershon FPCP 2004 October 4, 2004
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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!
Tim Gershon FPCP 2004 October 4, 2004
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BELLE KEK
Tim Gershon FPCP 2004 October 4, 2004
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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
Tim Gershon FPCP 2004 October 4, 2004
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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
Tim Gershon FPCP 2004 October 4, 2004
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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*
Tim Gershon FPCP 2004 October 4, 2004
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BELLE The Alphabet
With apologies to Z. Ligeti
Tim Gershon FPCP 2004 October 4, 2004
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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
Tim Gershon FPCP 2004 October 4, 2004
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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
Tim Gershon FPCP 2004 October 4, 2004
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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
100
150
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
Tim Gershon FPCP 2004 October 4, 2004
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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)
Tim Gershon FPCP 2004 October 4, 2004
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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 /
( 0.
0022
5 G
eV/c
0
10
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
10
20
30
)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 BABARpreliminary
Tim Gershon FPCP 2004 October 4, 2004
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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
Tim Gershon FPCP 2004 October 4, 2004
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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
Tim Gershon FPCP 2004 October 4, 2004
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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
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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 )
Tim Gershon FPCP 2004 October 4, 2004
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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 )
Tim Gershon FPCP 2004 October 4, 2004
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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
Tim Gershon FPCP 2004 October 4, 2004
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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%
Tim Gershon FPCP 2004 October 4, 2004
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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◦
Tim Gershon FPCP 2004 October 4, 2004
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BELLE Fits to Extract φ3
Fit B± samples separately, float rei(δ±φ3)
B± →(
KSπ+π−
)
DK±
276 candidate events (209 ± 16 signal)
-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±
69 candidate events (58 ± 8 signal)
-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◦
Tim Gershon FPCP 2004 October 4, 2004
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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◦
Tim Gershon FPCP 2004 October 4, 2004
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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
Tim Gershon FPCP 2004 October 4, 2004
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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
Tim Gershon FPCP 2004 October 4, 2004
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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
Tim Gershon FPCP 2004 October 4, 2004
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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
Tim Gershon FPCP 2004 October 4, 2004
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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
Tim Gershon FPCP 2004 October 4, 2004
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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!
Tim Gershon FPCP 2004 October 4, 2004
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BELLE Back-Up Slides
BACK UP
Tim Gershon FPCP 2004 October 4, 2004
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BELLE Comparison of SVD1 data and SVD2 data
Comparison for B± → DK±
SVD1: 152 × 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+->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◦
Tim Gershon FPCP 2004 October 4, 2004
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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
Tim Gershon FPCP 2004 October 4, 2004
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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
Tim Gershon FPCP 2004 October 4, 2004