B Decays to Open Charm (an experimental overview) Yury Kolomensky LBNL/UC Berkeley Flavor Physics and CP Violation Philadelphia, May 18, 2002

B Decays to Open Charm

(an experimental overview)

Yury KolomenskyLBNL/UC Berkeley

Flavor Physics and CP ViolationPhiladelphia, May 18, 2002

05/18/2002Yury Kolomensky, Open Charm

Decays

Contents of This Talk Focus on recent results, in particular “rare”

modes, accessible with high statistics samples at CLEO, Belle, and BaBar Due to time constraints, can’t cover the plethora of

modes and measurements shown on the front page

• Topics: BD(*)D(*) : Cabibbo-suppressed: BF, Angular

analysis, CPV BD(*)K : Cabibbo-suppressed: potential for Color-suppressed open charm decays B0D0(*)X0

B0DS+(*): Vub-suppressed


Decays

bccd decays: BD(*)D(*)

0B

0B

CPf

mixing

decay

CPfA

CPfA

CP

B0

D(*)-

D(*)+( )

B0D(*)-

D(*)+

( )

-ηeff sin2βsin(ΔmΔt)

Complementary to J/KS (bccs) Potential sensitivity to New Physics But: Cabibbo-suppression, penguin pollution, angular structure

_


Decays

First Things First: Observation of BD(*)D(*)

• First observation: CLEO, PRD 62, 032005 (2000) 9.7M B decays 8 signal events 6 observation

BR(B0 ! Dã+Dãà) =

(9:9+4:2à 3:3æ1:2) â 10à 4


Decays

Summary of BF MeasurementsSignificance BF (10)

CLEO (9 fb-1)

BaBar (20 fb-1)

Belle (20 fb-1)

CLEO (10 fb-1)

BaBar (20 fb-1)

Belle (30 fb-1, new)

Belle (partial reco)

CLEO (9 fb-1)

B0 ! Dã+Dãà

B0 ! DãæDç

B0 ! D+Dà

9:9+4:2à 3:3æ1:2

< 6:3

< 9:4

12:1æ4:1æ2:78:3æ1:6æ1:2

11:7æ2:6+2:2à 2:5

B0 ! Dã+Dãà

B0 ! DãæDç

14:8æ3:8+2:8à 3:1

BaBar

Belle


Decays

D*D final states are not CP eigenstates:

B0

D*+B0D

_

D*+

D _

D+

D* _

D+D*

_CPconjugation

strongphase

D*+D*- is not an eigenstate either: it is a combination of

CP-odd and CP-even amplitudes.

Measure CP content through angular (transversity)

analysis for decay products

Difficulties for CP Analysis


Decays

trttrttr

RR

22 cos2

3sin)1(

4

3

cos d

d1

The angular distribution asa function of one angle, tr:

Where Rt is a fraction of P-wave (CP-odd) component

Transversity Analysis for B0D*+D*-

RRtt = 0.22 = 0.22 0.18 0.18 0.03 0.03

signal fit

background fit

BaBar Results:


Decays

CP asymmetry in D*+D*- and D*+D-

D*D*

Ntag = 76Purity = 80%

D*DNtag = 85Purity = 52%

• BaBar 1999-2001 data sample: 56fb on (4S)

• Fit for Sf and Cf

• Separate Sf and Cf for D*+D- and D*-D+.

D*D*

S = - 0.05 0.45 0.05C = 0.12 0.30 0.05 D*DS+- = - 0.43 1.41 0.20C+- = 0.53 0.74 0.13S-+ = 0.38 0.88 0.05C-+ = 0.30 0.50 0.08

Expect 10-fold increase in statistics over the next 4 years


Decays

BD(*)0K Decays: Motivation

)(21000 DDD

)()()(2000

KDBAKDBAKDBA

1||)(0 ieAKDBA

ii eeAKDBA 2||)( 0

Determine through amplitude relationships (up to discrete ambiguities)

Gronau &Wiler; Dunietz (1991)

Potential for measuring CKM angle


Decays

Experimental Challenges• Rate suppressed by about factor of 10

compared to favored mode BD0

Small BF Need to reconstruct D0 into a CP eigenstate (another

Cabibbo penalty) Particle identification crucial

BDh DKK BDh DK

h=

h=

(BaBar preliminary)


Decays

BF ResultsCLEO (3 fb-1)

BaBar (55 fb-1, non-CP modes, new)

BaBar (55 fb-1, CP modes, new)

Belle (10 fb-1)

(5.5±1.4±0.5)%

(8.31±0.35±0.13)%

(8.4±2.0±0.8)%

(7.9±0.9±0.6)%

Belle (10 fb-1) (6.8±1.5±0.7)%

Belle (10 fb-1) (7.8±1.9±0.9)%

Belle (10 fb-1)

BaBar (20 fb-1, partial reco)

(7.4±1.5±0.6)%

(6.6±1.3±0.6)%

CLEO (9 fb-1) (6.1±1.6±1.7)*10-4

CLEO (9 fb-1) (3.7±1.5±1.0)*10-4

CLEO (9 fb-1) (7.7±2.2±2.6)*10-4

CLEO (9 fb-1) (3.8±1.3±0.8)*10-4

BF(Bà! D0ùà)BF(Bà! D0K à)

BF(B0! Dàù+)BF(B0! DàK +)

BF(B0! Dãàù+)BF(B0! DãàK +)

BF(Bà ! D0K ãà)

BF(Bà! Dã0ùà)BF(B à! Dã0K à)

BF(B0 ! DàK ã+)

BF(B0 ! DãàK ã+)BF(Bà ! Dã0K ãà)


Decays

Decays into D0CP

Belle: 29.1fb-1 sample (preliminary, 2002)Measure amplitude asymmetries for 3 samples:• Df : flavor eigenstate D0K+ (control sample)• D1(DCP=+1): CP eigenstates D0K+ and D0+

• D2(DCP=-1): CP eigenstates D0KS0, KSKS’, KSKSBaBar: 55 fb-1 sample (preliminary, 2002)• Df : flavor eigenstate D0K+ (control sample)• D+(DCP=+1): CP eigenstate D0K+

sinsin)()(

)()(00

00

rKDBBFKDBBF

KDBBFKDBBFA

CPCP

CPCPCP

r = jA(Bà! D0K à jjA(Bà! D0K à)j ù 0:1

Strong phase difference

Measure


Decays

Direct CP Asymmetry in BDKMode Expt ACP

B±Df K± Belle (new)

BaBar (new)

B±D1 K± Belle (new)

BaBar (new)

B±D2 K± Belle (new)

0:15æ0:24+0:07à 0:08

0:29æ0:26æ0:05

0:003æ0:089æ0:0360:044æ0:059(stat:only)

à 0:22æ0:24æ0:04

BelleB±D1 K±

E

BelleB±D2 K±

E

BelleB±Df K±

E


Decays

Color-Suppressed Open Charm Decays

Test of factorization in Class II BMcL0 decays

Class I (color-allowed)

Class II (color-suppressed)

A(B0 ! D+ùà) ø(m2

B à m2D) f ùFB! D(m2

ù)

A(B0 ! D0ù0) ø(m2

B à m2ù) f D FB! ù(m2

D)

a1(Dù)

a2(Dù)

“Naïve” Factorization:

a1 and a2 two phenomenological(but mode-independent) real parameters that can be determined from data (e.g. Neubert & Stech, hep-ph/9705292)


Decays

Color-Suppressed Modes: the Data

• Recent measurements of color-suppressed and color-favored BDXlight modes CLEO observation of B0D(*)00

(2001) Belle observation of B0D(*)00,

B0D(*)0B0D(*)0 (2001) CLEO new measurements of

color-allowed BD BaBar new measurement of

B0D(*)a

B0D0

B0D00


Decays

Color-Suppressed Modes: ResultsMode Experiment Significance BF (10-4) Prediction(*)

(10-4)

B0D00 CLEO (9 fb-1)

Belle (21 fb-1)

12.1

7.9

0.7

B0D*00 CLEO (9 fb-1)

Belle (21 fb-1)

5.9

3.2

1.0

B0D0 Belle (21 fb-1) 4.7 0.7

B0D*0 Belle (21 fb-1) 4.3 1.7

B0D0 Belle (21 fb-1) 3.8 0.5

B0D*0 Belle (21 fb-1) 3.6 0.6

BD0 CLEO (9 fb-1) 48

B0D CLEO(9 fb-1) 30

B0D(*)a BaBar (21 fb-1),

partial reco116

49:2æ1:1æ3:6

28:0æ1:2æ3:0

1:5+0:7à0:6æ0:4

1:4+0:5à0:4æ0:2

1:7+0:5à0:4

+0:3à0:4

3:4+1:3à1:1æ0:8

1:5+0:6à0:5

+0:3à0:4

2:9+0:4à0:3æ0:6

2:7+0:4à0:3æ0:6

2:2+0:6à0:5æ0:8

120æ7æ14


Decays

InterpretationsA(D0ù+)

A(Dàù+)

2p

A(D0ù0)

2 independent isospin amplitudes: and with non –zero phasedifference

A3=2A1=2

î I

CLEO analysis (2002, preliminary):

cosî I = 0:87+0:06à 0:05

cosî I = 0:87+0:06à 0:05

(CLEO data)(CLEO and Belle data)

» Non-zero strong phase differences: violates the basic assumption of naïve factorization. Sizable final-state rescattering effects in Class II processes

(similar analysis: Neubert & Petrov, hep-ph/0108103)


Decays

Motivation: measurement of sin(2+) using B0 D(*) Requires amplitude decomposition B0 D(*)+ and B0 D(*) Need to measure

Cabibbo-allowedBR=0.0030±0.0004

Cabibbo-suppressedBR not known

A(B0 D(*-) +)

A(B0 D(*+) -)D(*) =

~0.02

A(B0 Ds(*-) +)

SU(3)A(B0 D(*-) +)

Vub-suppressed Decay B0DS+(*)


Decays

Evidence for B Ds(*)

D

cos2C

BF (B D)BF (B Ds

) fD

2

fDs2

Measurement of the parameter DMeasurement of the parameter D

d

c

dB

Ds

b u

s

• Reconstructed Ds modes

DS , K*0K+ , KSK+, DS

*+DS+

K*0 KS

• Background rejection helicity angle (for Ds

, K*0 K+ modes) Fisher discriminant costhrust

Ds vertex probability

• (E , mES) of the reconstructed B

Also: potential for measuringVub/Vcb through ratios

BR(B0! D(ã)+S D (ã)à

BR(B0! D(ã)+S ùà)

Kim et al, PRD 63, 094506 (2001)(shaky theoretical grounds ?)

BaBar, 2002, 56 fb-1


Decays

Evidence for B Ds

14.9 4.1 events DD

BF( B Ds ) = ( 3.1 1.0 1.0 ) 105

BF( B Ds ) BF(Ds

) = ( 1.11 0.37 0.24 ) 106

BF(B Ds* 10-5 @ 90% CL

BF( B Ds ) = ( 3.1 1.0 1.0 ) 105

BF( B Ds ) BF(Ds

) = ( 1.11 0.37 0.24 ) 106

BF(B Ds* 10-5 @ 90% CL

B Ds :

significance of the signal = 3.5

BaBar PreliminaryBaBar Preliminary

B0DS+*

B Ds* :

significance of the signal = 2.2

Belle (21.3 fb): BF( B Ds ) < 10-5, BF( B Ds

K) < 7 10-5


Decays

B Ds: Unofficial(*)

Interpretation(*)Riccardo Faccini, private communication

Assuming SU(3) symmetry:

õDù = 0:02æ0:003(stat:) æ0:003(syst) æ0:001(Dàù+)

What is SU(3) uncertainty ?

Assuming naïve factorization (a la Kim et al) and using PDG value for BF(B0DSD*):

jVub=Vcbj = 0:080æ0:013(DSù stat:) æ0:013(DSDã stat:)

æ0:013(syst:) æ0:012(theo:)Experimental error 0.023: but is 15% theoretical uncertainty reliable ?

Need theoretical guidance


Decays

Outlook• Interesting new data coming from (old and

new) B factories Helicity structure and first CP asymmetries in

BD(*)D(*)

First measurements of direct CP asymmetries in BDK

First observations of color-suppressed decays open charm decays

First evidence for B Ds

More on the way: ten times more data at both BaBar and Belle by 2005

Documents

B Decays to Open Charm (an experimental overview) Yury Kolomensky LBNL/UC Berkeley Flavor Physics and CP Violation Philadelphia, May 18, 2002