b decays to open charm (an experimental overview) yury kolomensky lbnl/uc berkeley flavor physics...
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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
05/18/2002Yury Kolomensky, Open Charm
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
_
05/18/2002Yury Kolomensky, Open Charm
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
05/18/2002Yury Kolomensky, Open Charm
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
05/18/2002Yury Kolomensky, Open Charm
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
05/18/2002Yury Kolomensky, Open Charm
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:
05/18/2002Yury Kolomensky, Open Charm
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
05/18/2002Yury Kolomensky, Open Charm
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
05/18/2002Yury Kolomensky, Open Charm
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)
05/18/2002Yury Kolomensky, Open Charm
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)
05/18/2002Yury Kolomensky, Open Charm
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
05/18/2002Yury Kolomensky, Open Charm
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
05/18/2002Yury Kolomensky, Open Charm
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)
05/18/2002Yury Kolomensky, Open Charm
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
05/18/2002Yury Kolomensky, Open Charm
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
05/18/2002Yury Kolomensky, Open Charm
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)
05/18/2002Yury Kolomensky, Open Charm
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+(*)
05/18/2002Yury Kolomensky, Open Charm
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
05/18/2002Yury Kolomensky, Open Charm
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
05/18/2002Yury Kolomensky, Open Charm
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
05/18/2002Yury Kolomensky, Open Charm
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