Moriond EW 2005 Measurements of sin(2) Guillaume Therin 1

Measurements of sin(2 + ) / sin(21 + 3)

Guillaume TherinLPNHE – Paris

XLème rencontres de Moriond

BelleBaBar Results from and

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 2

CP violation in standard model

• Talk on time dependent analysis to constraint sin(2)

• Experimental results on B0 D– Partial reconstruction– Full reconstruction

• B0 DK branching ratio

CKM matrix Unitarity triangle

• Experimental constraints on • Need direct measurements of

VtdVtb*VudVub

*

VcdVcb*

sin (2) = 0.725 ± 0.037

See P.Krokovny’s talk for a review of measurements.

HFAG ICHEP04

http://ckmfitter.in2p3.fr

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 3

CP violation in B0D(*)

• Large branching fraction for favoured decay (~3x 10-3)

• Small BR for suppressed decay (~10-6)

• Small CP violating amplitude

Favored b c decay

*cb udV V A (*)

* i i iub cd rV V e A e e

Strong phasedifferenceCKM

angle

c0B

d

bu

d

*D

W +

b

d

bc

d

0B

u

*D

0B

d+

Suppressed b u decay

Determines the sensitivityof the method

r(D(*)) ≡ r(*) =A(B0 → D(*)- +)

≈ 0.02 A(B0 → D(*)- +)

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 4

Time-dependent decay rate distributions

• Measurements of S+ and S- determine 2+ and if r is an external input • Experiment : tag the flavour of the B with lepton and kaon categories

Mixing-Decay interferenceP(B0 → D(*) ,t) 1 C cos(md t) + S sin(md t)

P(B0 → D(*) ,t) 1 C cos(md t) - S sin(md t)

∞ ±

±

±

±

±±

±

C = 1 – r2 1 + r2

≈ 1

0Bcb

l+lepton tag

0Bc sb

K+

kaon tag

(4s)Tag B

Reco BK+

+

z

K+

t z/c

z

-s

-

neglecting terms

in o(r2)S± ≈ 2r sin ( 2 ± ) , |S±| 0.04<~±

∞

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 5

Possible CP violation on the tag side

Potential competing CP violating effects in B decays used for flavour tagging

signal side

tag side

2 sin(2 )cos

2 'sin(2 )cos '

2cos(2 )( sin 'sin ')

a r

b r

c r r

2 sin(2 )cos

2 cos(2 )si

0

nlep

b

a r

c r

Lepton tagsKaon and other flavour tags

(*)

* i i iub cd rV V e A e e ’

*cb udV V A +

P(B0 → D(*) - ,t) 1 + C cos(md t) + sin(md t) [± 2r sin(2) + 2r’ sin(2’)]∞

Kaon tag : expect CP violation comparable to signal → Modified time distributions

Observables : S+, S-

0Bc sb

K+

Observables a, b, c

c sK+

b0Bu

Long, Baak, Cahn, Kirkby, PRD68, 034010

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 6

Determination of r

• 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 B0Ds(*)+- using SU(3) symmetry

0B

d

u

*SD

bc

0B

d

d

u

*D

bc

scsV cdVSU(3)

r(D) = 0.020 ± 0.003 r(D*) = 0.015 ± 0.005 r(D) = 0.003 ± 0.006

I. Dunietz, Phys. Lett. B 427, 179 (1998)

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(2) Guillaume Therin 7

B0→D*: partial reconstruction

• 18710 ± 270 lepton tags

• 70580 ± 660 kaon tags

Lepton Tags

227MBB

Babar

PreliminarySignal

Combinatoric BBPeaking BBContinuum

D

All available statistics

Find events with two pions and examine the missing mass mmiss

Lepton Tags

kaon Tags

Mea

n va

lue

ACP= N(B0 tag) - N(B0 tag)

N(B0 tag) + N(B0 tag)

Preliminary

Preliminary

BaBar Collaboration,hep-ex/0408038 (previous reference)

*0 DBsoftD

0

X

fast

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 8

plane whith experimental constraints on sin(2β+γ) and β (from BaBar).

Preliminary

Preliminary

B0→D*: partial reconstruction (interpretation)

|sin(2β+γ)|>0.62 (0.35) @ 68 (90)%CL

• Adding 30% theoretical error on r(D*) for different hypotheses• Using the Feldman Cousins method

BaBar Collaboration,hep-ex/0408038 (previous reference)

227MBB

Babar1

- C

L

r = 0.015 ± 0.005 ± 0.005

90 %

68 %

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 9

S+ = 0.035 ± 0.041 ± 0.018S- = 0.025 ± 0.041 ± 0.018

154MBB

helicity angle calculated with soft

SF : Sign(fast) = Sign(l) OF : Sign(fast) = - Sign(l)

• 2823 Same Flavour (SF)

• 10078 Opposite Flavour (OF)

B0→D*: partial reconstruction (lepton tag)Belle Collaboration,hep-ex/0408106

PreliminaryPreliminaryPreliminary Preliminary

PreliminaryPreliminary

Fit : Signal + Background

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 10

110MBB

BabarB0→D(*): full reconstruction

BaBar Collaboration,hep-ex/0408106

• 7611 ± 97 B → D

• 7068 ± 89 B → D*

• 4400 ± 79 B → D

D*+

0B

0B

D*+ D*-

0B

0B

D*-

B → D* ±

±

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 11

D154MBB

D*

D*+

0B

0B

D*+

D*-

0B

0B

D*-

Assuming δ = 0 or π (factorisation) :

B0→D(*): full reconstruction

Estimation of CP violation on the tag side with B→D*l

Use kaon and lepton tags

Belle Collaboration, PRL 93 (2004) 031802

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 12

Summary of sin results with B0 → D(*)

a(D*)c(D*)

a(D)

c(D)

a(D)

c(D)

Partially rec. Fully rec.Partially rec.Fully rec.

-0.034 ± 0.014 ± 0.009 –0.049 ± 0.031 ± 0.020 –0.031 ± 0.028 ± 0.018 0.060 ± 0.040 ± 0.019

-0.019 ± 0.022 ± 0.013 0.044 ± 0.054 ± 0.033 –0.004 ± 0.028 ± 0.018 0.049 ± 0.040 ± 0.019

–0.032 ± 0.031 ± 0.020 –0.062 ± 0.037 ± 0.018

–0.059 ± 0.055 ± 0.033 –0.025 ± 0.037 ± 0.018

–0.005 ± 0.044 ± 0.021

–0.147 ± 0.074 ± 0.035

227 MBB 110 MBB 152 MBB 152 MBB

a = 2 r sin(2) cos (i) c = 2 r cos(2) sin (i)

r(D) = 0.020 ± 0.003 r(D*) = 0.015 ± 0.005 r(D) = 0.003 ± 0.006

without any errors coming from theoretical hypotheses

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 13

Interpretation of sin(2) assuming SU(3)

www.utfit.org

90 %

68 %

Assign 30 % theoretical error on r(D*), r(D) and r(D)

68 % 90 %

Bayesian approach

|sin()|>0.74 @68% CL

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 14

Constraining sin(2) with B0→D(*)0Ks

uc

dd

0B

0(*)DcsV

*ubV

b

s 0(*)K

bc amplitude bu amplitude

)( 000 KDBAa ii eera 0

cu

dd

0B

0(*)DusV

*cbV

b

s 0(*)K

• Small branching fraction for favoured decay (~3x 10-5)• Large asymmetry

• B0D(*)0Ks with any D0 measures sinwith time dependent analysis

• B0D(*)0K*0 with D0CP eigenstate measures (self-tagging mode ,not this talk)

r0 =A(B0 → D0 )

≈ 0.4 A(B0 → D0 )

For r0=0.4, an error of 0.5 on sin() is expected with 550 MBB .

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 15

Branching ratios of B0→D(*)0Ks 274MBB

Belle Collaboration,hep-ex/0408108

124MBB

Babar

D0 mass

sideband

Preliminary

mes (GeV)BaBar Collaboration,hep-ex/0408052

B( ) = 3.72 ± 0.65 ± 0.37B0 → D0 K0B → D0 K0B( ) = 6.2 ± 1.2 ± 0.4

B → D*0 K0B( ) = 4.5 ± 1.9 ± 0.5 B( ) = 3.18 ± 0.32B0 → D*0 K0 +1.25-1.12

r0( ) < 0.39 @ 90%D0 K*0Average of B0 and B0

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 16

Conclusions

• Many different approaches to measure have been investigated with similar sensitivity.

• Limits on | sin(2)| with time dependent analysis were updated

• Measurements on sin(2)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 can be combined with other DK measurements (also no penguin contribution)

• With higher statistics, methods to constraint sin(2) with B0 → D(*)0 Ks will play a role as well ( r ≈ 0.4 )

www.utfit.org

|sin()|>0.74 @68% CLAssuming SU(3) symmetry

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 17

SU(3) breaking and Ds0

• 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+0) will be measured – expected to be ~10-6– SU(2) partner of D+-

– SU(3) partner of Ds0 will be able to test SU(3)

• First search of BDs0

– Consistent with SU(2) prediction from Br(Ds )

Br(BDs0) = 1.6 10-5

Small statisticsAnnihilations around

Br(BDs0)<2.8 10-5@90% C.L.

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 18

W-exchange diagrams

B0D(*)+- has contributions also from W exchange

0B

dd

u

*D

b

c

d

0B

d

bc

u

D(*)-, Ds(*)-

d,s

d,s

Unfortunately this sets a limit only on the annihilation on the cabibbo allowed process. Assuming it is the same is controversial

Constrained by smallness of Br(B0Ds-K+)/Br(B0D-+)=(1.4±0.5)10-2

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 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) < 7 10-6

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(2) Guillaume Therin 20

Avoiding colour suppression : B0→D±KS± (88 MBB)

bc amplitude bu amplitude

ds

dd0B (*)D

*cbV

usV

b

0Kc

ud

ds

dd0B

(*)D

ubV

*csV

b

0Ku

cd

mixing 2ie00 / BB ieA

D±K*± →

• Method has two advantages :– Avoids colour suppression in b→u– Integrating over Dalitz plane removes

ambiguities in eventual 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

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 21

Data samples collected with Belle and BaBar

BELLE @ KEK-B Accelerator BaBar @ PEP-II Accelerator

350 fb-1 integrated luminosity275 million BB events

254 fb-1integrated luminosity227 million BB events

Moriond EW 2005 Measurements of sin(2) Guillaume Therin 22

sin() in Pictures

• r exaggerated (x5 expectation) to enhance visual effect– Small values of r significantly reduce sensitivity of the method

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