1. Measurements of sin(2b + g) / sin(2f1 + f3)
Belle
BaBar
Results from
and
Guillaume Therin
LPNHE – Paris
XLème rencontres de Moriond
Moriond EW 2005
Measurements of sin(2b+g)

2. CP violation in standard model
CKM matrix
Unitarity triangle
VudVub *
a/f2
VtdVtb *
g/f3
b/f1
sin (2b) = ± 0.037
HFAG
ICHEP04
VcdVcb *
Experimental constraints on a
Need direct measurements of g
Talk on time dependent analysis to constraint sin(2b+g)
Experimental results on B0  D(*) p/r
Partial reconstruction
Full reconstruction
B0  D(*)0K(*)0 branching ratio
See P.Krokovny’s talk for a review of g measurements.
Moriond EW 2005
Measurements of sin(2b+g)

3. CP violation in B0D(*)p/rg
Favored b  c decay
Suppressed b  u decay
Strong phase
difference
Determines the sensitivity of the method
CKM angle
Large branching fraction for favoured decay (~3x 10-3)
Small BR for suppressed decay (~10-6)
Small CP violating amplitude
r(D(*)p) ≡ r(*) =
A(B0 → D(*)- p+)
≈ 0.02
Moriond EW 2005
Measurements of sin(2b+g)

4. Time-dependent decay rate distributions- K+
-s
Tag B K+
U(4s)
Reco B z
Dz/gbc + Dz
Mixing-Decay interference ∞
P(B0 → D(*) p ,Dt) C cos(Dmd Dt) + S sin(Dmd Dt)
P(B0 → D(*) p ,Dt) C cos(Dmd Dt) - S sin(Dmd Dt) ∞
C =
1 – r2
1 + r2
≈ 1
neglecting terms
in o(r2)
S± ≈ 2r sin ( 2b+g ± d ) , |S±|
< ~
Measurements of S+ and S- determine 2b+g and d if r is an external input
Experiment : tag the flavour of the B with lepton and kaon categories l+ K+
lepton tag
kaon tag
Moriond EW 2005
Measurements of sin(2b+g)

5. Possible CP violation on the tag side
Long, Baak, Cahn, Kirkby, PRD68,
Potential competing CP violating effects in B decays used for flavour tagging K+ K+ ’ +
Kaon tag : expect CP violation comparable to signal → Modified time distributions
signal side
tag side ∞
P(B0 → D(*) - p+ ,Dt) C cos(Dmd Dt) + sin(Dmd Dt) [± 2r sin(2b+g+d) + 2r’ sin(2b+g±d’)]
Kaon and other flavour tags
Lepton tags
Observables : S+, S-
Observables a, b, c
Moriond EW 2005
Measurements of sin(2b+g)

6. Measurements of sin(2b+g)
Determination of r
I. Dunietz, Phys. Lett. B 427, 179 (1998)
Simultaneous determination of sin(2+) and r from time-evolution is not possible with current statistics  Need r as external inputs
Estimate amplitude ratios from B0Ds(*)+- using SU(3) symmetry
SU(3)
r(D) = ± r(D*) = ± r(Dr) = ± 0.006
Assuming several hypotheses :
Assuming factorisation in SU(3) symmetry
W-exchange and annihilation diagrams neglected
without any theoritical errors
Moriond EW 2005
Measurements of sin(2b+g)

7. B0→D*-p+: partial reconstruction
Babar
BaBar Collaboration,hep-ex/ (previous reference)
fast
Lepton Tags
227MBB
Find events with two pions and examine the missing mass mmiss
Preliminary
All available statistics
Preliminary
kaon Tags
Signal
Combinatoric BB
Peaking BB
Continuum
D*r
ACP=
N(B0 tag) - N(B0 tag)
N(B0 tag) + N(B0 tag)
Preliminary
Lepton Tags
18710 ± 270 lepton tags
Mean value
70580 ± 660 kaon tags
Moriond EW 2005
Measurements of sin(2b+g)

8. Measurements of sin(2b+g)
B0→D*-p+: partial reconstruction (interpretation)
Babar
BaBar Collaboration,hep-ex/ (previous reference)
227MBB
Adding 30% theoretical error on r(D*p) for different hypotheses
Using the Feldman Cousins method
r-h plane whith experimental constraints on sin(2β+γ) and β (from BaBar).
r = ± ± 0.005
1 - CL
Preliminary
68 %
90 %
Preliminary
|sin(2β+γ)|> (90)%CL
Moriond EW 2005
Measurements of sin(2b+g)

9. Measurements of sin(2b+g)
B0→D*-p+: partial reconstruction (lepton tag)
Belle Collaboration,hep-ex/
154MBB
SF : Sign(pfast) = Sign(l)
OF : Sign(pfast) = - Sign(l)
Preliminary
Preliminary
Preliminary
Preliminary
Preliminary
Preliminary
helicity angle calculated with psoft
Fit : Signal + Background
2823 Same Flavour (SF)
10078 Opposite Flavour (OF)
S+ = ± ± 0.018
S- = ± ± 0.018
Moriond EW 2005
Measurements of sin(2b+g)

10. Measurements of sin(2b+g)
110MBB
Babar
B0→D(*)-p+/r+: full reconstruction
BaBar Collaboration,hep-ex/
D*- p+
D*+ p-
B → D* p
D*- p+
D*+ p-
7611 ± 97 B → Dp
7068 ± 89 B → D*p
4400 ± 79 B → Dr
Moriond EW 2005
Measurements of sin(2b+g)

11. Measurements of sin(2b+g)
154MBB
B0→D(*)-p+: full reconstruction
Belle Collaboration, PRL 93 (2004)
D*p Dp
Use kaon and lepton tags
Estimation of CP violation on the tag side with B→D*l n
D*+ p-
D*- p+
Assuming δ = 0 or π (factorisation) :
D*+ p-
D*- p+
Moriond EW 2005
Measurements of sin(2b+g)

12. Summary of sin(2b+g) results with B0 → D(*)p/r
227 MBB
110 MBB
152 MBB
152 MBB
Partially rec.
Fully rec.
Partially rec.
Fully rec.
a(D*p)
–0.049 ± ± 0.020
0.060 ± ± 0.019
± ± 0.009
–0.031 ± ± 0.018
c(D*p)
± ± 0.013
0.044 ± ± 0.033
–0.004 ± ± 0.018
0.049 ± ± 0.019
a(Dp)
–0.032 ± ± 0.020
–0.062 ± ± 0.018
c(Dp)
–0.059 ± ± 0.033
–0.025 ± ± 0.018
a(Dr)
–0.005 ± ± 0.021
c(Dr)
–0.147 ± ± 0.035
a = 2 r sin(2b+g) cos (di)
c = 2 r cos(2b+g) sin (di)
r(D) = ± r(D*) = ± r(Dr) = ± 0.006
without any errors coming from theoretical hypotheses
Moriond EW 2005
Measurements of sin(2b+g)

13. Interpretation of sin(2b+g) assuming SU(3)
Assign 30 % theoretical error on r(D*p), r(Dp) and r(Dr)
Bayesian approach h
68 %
90 %
68 %
90 % r
2b+g CL
Moriond EW 2005
Measurements of sin(2b+g)

14. Constraining sin(2b+g) with B0→D(*)0Ks
bc amplitude
bu amplitude
r0 =
A(B0 → D0 K0)
≈ 0.4
Small branching fraction for favoured decay (~3x 10-5)
Large asymmetry
B0D(*)0Ks with any D0 measures sin2b+g with time dependent analysis
B0D(*)0K*0 with D0CP eigenstate measures g (self-tagging mode ,not this talk)
For r0=0.4, an error of 0.5 on sin(2b+g) is expected with 550 MBB .
Moriond EW 2005
Measurements of sin(2b+g)

15. Branching ratios of B0→D(*)0Ks
124MBB
Babar
274MBB
Branching ratios of B0→D(*)0Ks
D0 mass
sideband
Preliminary
mes (GeV)
BaBar Collaboration,hep-ex/
Belle Collaboration,hep-ex/
B → D0 K0
B( ) = 6.2 ± 1.2 ± 0.4
B( ) = 3.72 ± 0.65 ± 0.37
B0 → D0 K0
B( ) = ± 0.32
B0 → D*0 K0
+1.25
-1.12
B → D*0 K0
B( ) = 4.5 ± 1.9 ± 0.5
r0( ) < 90%
D0 K*0
Average of B0 and B0
Moriond EW 2005
Measurements of sin(2b+g)

16. Measurements of sin(2b+g)
Conclusions
Many different approaches to measure g have been investigated with similar sensitivity.
Limits on | sin(2b+g) | with time dependent analysis were updated
Measurements on sin(2b+g) still statistics limited.
Some analyses need to be updated with all available statistics
Need to estimate CP violation on the tag side to use completely kaon tag
Results on g can be combined with other DK measurements (also no penguin contribution)
With higher statistics, methods to constraint sin(2b+g) with B0 → D(*)0 Ks will play a role as well ( r ≈ 0.4 ) CL
Assuming SU(3) symmetry
Moriond EW 2005
Measurements of sin(2b+g)

17. Measurements of sin(2b+g)
SU(3) breaking and Dsp0
SU(3) has been proven to hold at a few % level for factorizable processes, but here the heavy meson is emitted and factorization does not hold
Note that the use of the form-factors automatically assumes factorization
In the future BR(D+p0) will be measured
expected to be ~10-6
SU(2) partner of D+p-
SU(3) partner of Dsp0  will be able to test SU(3)
First search of BDsp0
Consistent with SU(2) prediction from Br(Dsp )
Br(BDsp0) =
Small statistics
Annihilations around
Br(BDsp0)<2.8 C.L.
Moriond EW 2005
Measurements of sin(2b+g)

18. Measurements of sin(2b+g)
W-exchange diagrams
B0D(*)+p- has contributions also from W exchange
Constrained by smallness of Br(B0Ds-K+)/Br(B0D-p+)=(1.4±0.5)10-2 c
D(*)-, Ds(*)-
d,s
d,s
p+,K+ u
Unfortunately this sets a limit only on the annihilation on the cabibbo allowed process. Assuming it is the same is controversial
Moriond EW 2005
Measurements of sin(2b+g)

19. D(*)+Ks : probing annihilations
SU(2) partner of D0K+
Expected to be ~10-7 but could get large contributions from rescattering
Br(B D+Ks) < xxx 10-6
Br(B D*+Ks) <
Note:
Br(B D0K+) =(3.7±0.6)10-4
Br(B D*0K+)=(3.6±1.0)10-4
Moriond EW 2005
Measurements of sin(2b+g)

20. Avoiding colour suppression : B0→D±KSp± (88 MBB)
bc amplitude
bu amplitude
mixing
Method has two advantages :
Avoids colour suppression in b→u
Integrating over Dalitz plane removes ambiguities in eventual g extraction
First experimental step complete :
Branching fraction measurement
Currently, Too few events for TD analysis
1/3 of events are NOT in the K* region
D±K*± →
Moriond EW 2005
Measurements of sin(2b+g)

21. Data samples collected with Belle and BaBar
KEK-B Accelerator
PEP-II Accelerator
350 fb-1 integrated luminosity
275 million BB events
254 fb-1integrated luminosity
227 million BB events
Moriond EW 2005
Measurements of sin(2b+g)

22. Measurements of sin(2b+g)
sin(2b+g) in Pictures
No Interference  CP Violation
CP Violation only in fully reconstructed B0: r  0
CP Violation in both tag and fully reconstructed B0s: r  0 and r’  0
r exaggerated (x5 expectation) to enhance visual effect
Small values of r significantly reduce sensitivity of the method
Moriond EW 2005
Measurements of sin(2b+g)