hadronic b decays to double-charm final states

Hadronic B DecaysTo Double-Charm Final States

SERGIO GRANCAGNOLOL.Lanceri – J.P.Lees

BINP Novosibirsk

Particle Physics Seminar

http://physics.units.it/

10 Feb 2006 Sergio Grancagnolo 2

Outline

• Introduction

• The BaBar Detector at PEP-II

• The DsJ observations

• Theoretical Interpretations of DsJ

• Analysis of BD(*)DsJ decays

• Results: branching fractions and angular distributions

• Comparison with models and conclusions

Introduction


The Standard Model

• Fundamental particles:– 6 quark , 6 leptons– 4 interactions

• The model works well but there are several issues to be understood, for instance:– Higgs boson– Supersymmetry– Strong interactions

b

t

s

c

d

u

e

e

W,Z bosons


Quantum Numbers Of The Quarks

d u s c b t

Q – electric charge -1/3 +2/3 -1/3 +2/3 -1/3 +2/3

Iz – isospin -1/2 +1/2 0 0 0 0

S - strangeness 0 0 -1 0 0 0

C - charm 0 0 0 +1 0 0

B - bottomness 0 0 0 0 -1 0

T - topness 0 0 0 0 0 +1

PropertyQuark


CKM Matrix and Unitary Triangle

Unitary relationship VudVub*+VcdVcb

*+VtdVtb*=0

W+

Vijqj=d,s,b

qi=u,c,t

VcdVcb

*

Vtd V

tb *

V udV ub

*Unitary triangle

tbtstd

cbcscd

ubusud

VVV

VVV

VVV

V

A complex phase in the V matrix can be a source of CP violation in B decays

049.0736.0)2sin(

VV†=I

CKM


Mesons in the Quark Model

• Quarks exist only in baryons and mesons

• Mesons are made of a quark-antiquark pair

• As an example:

• Mesons are not stable– Mass, charge and lifetime are main characteristics– Meson width ~ 1/lifetime

depends on the allowed decay modes

K+ D0 B- Sud us cu bu bb

__ _ _ _


Heavy Quark Approximation

q

Q_

In the heavy quark approximation

mq<<mQ,, mQ

sQ, j conserved

However J, P good quantum numbers

ℓ

sQsq

sQ ,sq =+½,-½

Heavy and light quark spins

ℓ=0,1,… Orbital momentum

j=ℓ+sq

Light quark total angular momentum

P=(-1)ℓ+1 Parity

J=j+sQMeson total angular

momentum


Charmed Mesons Spectroscopy

JP cu csExpected

width

(0,1) D,D* D,D*s narrow

(0+,1+) D*0,D´1 D*

s0,D´s1 broad

(1+,2+) D1,D*2 Ds1,D*

s2 narrow

• States with ℓ=1 can decay strongly with emission of a pseudoscalar meson– j=1/2 emission in s-wave– j=3/2 emission in d-wave

• D*0,D´1 observed by CLEO, Focus and Belle

– Broad resonances as expected

ℓ=0

ℓ=1 )21(Pj )23(Pj

_ _

broad ~100 MeV

narrow ~10 MeV


The expected cs Meson Spectra

States expected but not observed

• Masses over threshold DK(*)

• Broad states (large widths)

*

_

2.51 GeV

2.36 GeV

M.Di Pierro, E.EichtenPhys. Rev. D64, 114004 (2001)


• Spectator quark model

the other u,d quark enters the final state without participating to the interaction

• In hadronic decays, could be tested the factorization hypothesis:

the final hadrons are produced independently

B Meson Decay

Since mb >>mu,d

bcW* whereW* ℓ

W* qiqj

_semileptonic

hadronic

the B meson decay dominantly through

W* virtual boson

the disintegration of the b quark. The main transition

is the weak decay


_ ___

_

Exclusive Hadronic B decays

• In exclusive decays all particles in final state are reconstructed

• Double charm decays contains two mesons with charm quarks

• Examples:

B,B0 D(*)0,D

Ds

B,B0 D(*)0,D

D(*)0

K(*)

_BDsD

B DDK

The BaBar Experiment


The PEP-II B-factory at SLACPEP-II is a high luminosity, asymmetric, e+e collider

Lint=254 fb-1

Ldesign = 3 x 1033 cm-2s-1

Lpeak = 9.21 x 1033 cm-2s-1

Integrated luminosity

year

113fb-1


B-factory Cross Sections

e+e cross-section (nb)

bb 1.05

cc 1.30

uu, dd, ss

2.09

0.94

1.16

e+e ~40

The boost allows a separation of the two B vertices.

E(e+) = 3.1 GeV E(e) = 9.0 GeV

_

_

_

_ _[

e+e

h

adro

ns](

nb)

√s(GeV)

Ecm=10.58 GeV

boost: =0.56

(4S) BB_

e+e bb on-resonance BB

“coontinuum” e+e cc high momentum charmed particles

_

_ _


Cerenkov Detector (DIRC)

1.5 T solenoid Electromagnetic Calorimeter

Drift Chamber

Instrumented Flux ReturnSilicon Vertex

Tracker

e+ (3.1 GeV)

e- (9 GeV)

BABAR Detector%85.1%32.2 4/1 E

EE

%45.0%13.0)(

TT

T pp

p

The DsJ observations


• BaBar discovered a new particle decaying into Ds0

– c and s quarks– Mass < DK threshold– Width < 10 MeV

• Seen by Belle and CLEO• Is this the expected Ds0 ?

DsJ(2317) Discovery*

BaBar collaborationPhys.Rev.Lett.

90, 242001 (2003)

_

*+

+

+

Ds0 Invariant mass

GeV

m=2.317GeV

+

Inclusive selection of high momentum charmed meson from coontinuum e+e cc

_


DsJ(2460) Discovery

• CLEO observed another state decaying to Ds 0!

– c and s quarks– Mass < (DK)* threshold– Width < 10 MeV

• Observed also decay modes:– Ds, Ds+

• Is this the expected Ds1?

+

2.25 2.5 2.75

Eve

nts/

7 M

eV/c

2

*+

++

+

CLEO collaborationPhys. Rev. D68, 032002 (2003)

Seen by BaBar and Belle

m=2.460 GeV

Ds 0 Invariant mass *+_

GeV

80

60

40

20

0


The Observed cs Meson Spectra

New states observed

• Masses below threshold DK(*)

• Narrow states

*

_

2.51 GeV

2.36 GeV


• Isospin symmetry is not exact

• Violation already observed in Ds* Ds0 decay

Isospin Violation in These Decaysmeson Ds,Ds

*,DsJ D0 K+ 0

qq cs cu us uu+dd

Isospin (I,Iz) (0,0) (½,-½) (½,+½) (1,0)

Invoked oscillation

DK Ds0

Energy forbidden

Energy conserving

Isospin allowed

Isospin violating

DsJ Ds0

_ __ _ _ __

P.L.Cho, M.B.Wise

Phys.Rev.D49: 6228-6231,1994

ss

(0,0)

Theoretical Interpretations of DsJ

Standard interpretations

Exotic interpretations


• Quark models– Potential: coulombian

• (0-,1-),(0+,1+) chiral partners– doublets mass splitting via chiral symmetry breaking

– transitions via scalar meson

Standard interpretationsEntia non sunt multiplicanda praeter necessitatem (G.Occam)

Cahn, Jackson

need to adjust a posteriori input parameters, predict mass higher than observed or not reproduce non-strange charmed mesons spectra

hyperfine splitting for charmed mesons (D, D*, etc.) marginally compatible with experiments

Bardeen, Eichten, Hill

Lucha, Schoberl

+ linear

+ spherical not linear


• Unitarized chiral models– generalization replacing a light quark with an

heavy quark

• Non-perturbative methods– lattice QCD

– QCD sum rules

Standard interpretations

several new mesons predicted not observed

initial difficulties to reproduces masses, reproduces mass splitting

low accuracy

Dai, Huang, Liu, Zhu

Bali

Beveren, Rupp


Exotic Interpretations

cs DK 4-qmixing

di-quark pairs

Ds molecule

Ds

DK molecule

D

K

qq qqqq

D

K

qq

qq_

_

_ __

_

Maiani, Piccinini, Polosa, Riquer

Barnes, Close, Lipkin

Szczepaniak

Browder, Pakvasa, Petrov

Analysis of BD(*)DsJ decays

Branching ratios: Method

Event selection

Signal and Backgrounds

Efficiency and “cross-feed”


BD(*)DsJ Decays• Exclusive DsJ production: expected to be dominant

• Allow to measure DsJ quantum numbers

• In principle, allow to discriminate between conventional and multi-quark scenarios compared with other B decays such as BD(*)Ds and BD(*)D(*)K

• If the DsJ is the conventional cs state should be produced in the following graph:

Weak external W emission

_ _

_

B,B0 D(*)0,D

DsJ

___

Same graph as BD(*)Ds similar branching ratios could be expected

_


• We search for DsJ particles looking at the 12 combinations:

• With DsJ decays:

• We measure branching ratios, quantum numbers JP

BD(*)DsJ Decays (II)

ssJ

ssJ

DD

DD

)2460(

)2460( 0*0* )2317( ssJ DD

sJsJ

sJsJ

DDBDDB

DDBDDB0*0

*00


Subdecay Modes

Intermediate particles are reconstructed in the following modes:

ss DD*

KD

0* DD

K

sD

0 K K

KD0

KK KK 0*

)892(

Total: 60 different submodes combined to

give the 12 combinations

0D

000* DD Green::clean modes


Analysis Goal and Method• We aim to measure branching ratios Bri (i=1…12) of

the exclusive double charm two body production of DsJ(2317)+

and DsJ(2460)+ in B0 and B+

• nisig number of signal candidates for mode i

– after combinatorial background subtraction

• nixfd number of crossfeed events for mode i

– contains background from other signal modes

• ireconstruction efficiency from simulation• NBB = [122.0 ± 0.6(stat) ± 1.3(syst)] 106 (113 fb-1)

BBi

ixfd

isigi

N

nnBr

*

_


• Reconstruct the chain:

• Reconstruct tracks (K,) and photons ()

• Select D0, Ds , , 0 computing invariant masses

• Use beam energy kinematic constraint

• Fit nisig in Ds invariant mass distribution

A specific example: B0D*DsJ(2460)+

B0

K+

D0_

DsJ(2460)+*

Ds

+

K+

K

*

D*


Event Selection: Invariant MassesInvariant mass: 2

212

21 ||)( ppEEm

D0 K Ds

D* D0 KK

0.99 1.02 1.04

40000

20000

0

m(GeV/c2)

Particles masses are set to their nominal values (mass constraint)


Event Selection: B candidates• Compute p*

B and E*B

from selected D*, Ds,

• Use the B-factory constraint E*beam to compute:

5.272<mES<5.288 GeV

E|<32MeV

better resolution

uncorrelation

Sidebands to estimate background outside signal box

mES

ΔE

**beamB EEE 2*2* )()( BbeamES pEm

Use of beam kinematic variables

“Signal box”:


E resolution

• Same resolution for all the submodes

• A systematic error will take in account differences between data and simulation

Missing energy effect

Simulation of signal events

Data candidates in mES signal region

(E)=16.1 (E)=18.9

Cross-hatched background from sidebands


E resolution (II)

(E) simulation data

0 12 16

16 20

Final values used in selection

(MeV)

Better resolution for modes with a 0 (mass

constraint)


Background Rejection

• Reduction of the combinatorial background• Simulated signal events selected in signal region• Background from data events selected in DsJ mass

sideband region• Curves represent

fraction of events cut bym(D0)> mcut(D0)

• Optimal cut set at themaximum separationbetween two samples

Gev/c2

Events rejected:

25% signal

75% backgrd

m(D*) cut

m(D*)>2.4GeV/c2


Optimization• Maximized the significance ratio:

S = simulated signal events in signal region

B = background from data in m(DsJ) sidebands

BS

S

Tried different cut levels for D and Ds using PID, vertexing and helicity cut

Tried different numbers of cut for variables: E, m(Ds), m(D)

1.94 2.0m()

5000

200002500

40000

cos(hel)-1 1

cos(hel) mass

Cleaner modes require less stringent cuts


Fit nisig in DsJ(2460)+ Ds

+

• Finally, in selected candidates: m(Ds)

• Fit the background shape with a polynomial

• Fit the signal peak with a Gaussian of fixed width– =12 MeV

– estimated in data

• Events in the signal peak: ni

sig = 53.0±7.7

Ent

ries

/10

Mev

/c2

GeV/c2

m(Ds)

significance=11.7


Efficiency and Cross-feed

• From gi=60k simulated signal events for each mode i

– Efficiency:

nisim = number of B0D*DsJ(2460)+ events reconstructed in

the corresponding simulated sample

– Total cross-feed:

nijsim = number of B0D*DsJ(2460)+ events reconstructed in

the simulated sample (mode j)

fij = cross-feed from the mode j to the mode i

i

isimi

g

n

j

j

ijev

ixfd BrfNn

j

ijsimij

g

nf ;

Typical efficiency range: 1-10%

depending on the presence of photons, soft tracks, stringent cuts, etc.


m(DsJ)

GeV/c2

Efficiency

i=(4.63±0.08)%

fij=(0.82±0.04)%

nisim = 2778

gi=60000

nijsim = 24

gj=60000

Cross-feed

Generated mode: B0D*Ds1

Ds

Generated mode: B0D*Ds1

Ds+

Narrow Cross-feed

Narrow:xfdsig

Reconstructed mode: B0D*Ds1

Ds


Cross-feed

m(DsJ)

GeV/c2

Efficiency

i=(2.25±0.07)%

Generated mode: B0DDs1

Ds*

Cross-feed

fij=(0.24±0.02)%


Ds

fij=(0.27±0.02)%


Ds

Wide Cross-feed

nisim = 1350

gi=60000

nisim = 144

gi=60000

nisim = 162

gi=60000

Wide:xfd 2.5 sig

Reconstructed mode: B0DDs1

Ds


Branching Ratios and Cross-feedAn iterative procedure is needed:

• Compute for each mode i without considering cross-feed

• Estimate nixfd using Brj and the cross-feed fij

from all the modes• Subtract the number of cross-feed events• Compute the corrected branching ratio

• Recompute the cross-feed iterating point 2-4 until convergence.

iev

isigi

N

nBr

iev

ixfd

isigi

N

nnBr

__

ixfd

isig nn

Results


s=3.1

s=5.5

s=5.2

s=2.5

s=5.1

s=4.2

s=7.4

s=7.7

s=4.3

s=5.0

s=11.7

s=6.0

Fit Results And Significance


Main Systematic Errors• Tracking efficiency 9%• /0 efficiency 5%• Background fitting model 5%

– Tried exponential instead of polynomial to fit background

• E width 5%– Changed the width of the E

signal region by ±3 MeV

• DsJ width 3%– Varied by ±1 MeV the of the

Gaussian (12 MeV) that fit the signal

Depends on the tracks or photons number

Modes with D*0 more affected


Branching Ratios Results

NEW!

NEW!

NEW!

NEW!

NEW!

NEW!

Phys.Rev.Lett.93:181801,2004

Measurements with significance>5


DsJ(2460)+ Angular Analysis (I)

• Use B0DsJ+D and B+ DsJ

+D0 with DsJ+Ds

• B DDsJ+ is a transition 0 0 JP so DsJ is polarized

• Compute the helicity angle h of DsJ+Dsand compare

with the predictions for JP=1+ and JP=2+ (0+ forbidden)

_


DsJ(2460)+ Angular Analysis (II)

Simulation is used to correct for detector acceptance

DsJ events are fitted separately in 5 cos(h) bins

not used cut m(D)>2.3


DsJ(2460)+ Angular Analysis (III)

• Expected distribution for JP=1+ is:

1-cos2(h)• Distribution compatible

with this case– 2/d.o.f.=3.9/4– Supporting the Ds1

+ hypothesis for this state

• Comparison with JP=2+ hypothesis is also provided– 2/d.o.f.=34.5/4


Some Comparisons With Models

• Branching ratios smaller than the corresponding BD(*)Ds

(*)

– Factorization effects could be important and could not cancel in the ratios RD0,1

– support a multiquark hypothesis

• Observation of electromagnetic DsJ(2460)+ decay– supports a conventional cs picture

• In agreement with prediction from chiral multiplets we measure:

Colangelo, De Fazio, Ferrandes: Mod.Phys.Lett.

A19:2083,2004

Godfrey Phys.Lett.

B568:254,2003

Bardeen, Eichten, Hill: Phys.Rev.

D68:054024,2003

_


Conclusions

• We combine 60 different final states to obtain 12 branching ratios BD(*)DsJ measurement with

– The modes BD*DsJ with a D* or a D*0 are first observations

– Extraction of JP=1+ quantum numbers of DsJ(2460)+

sssJ DDD ,)2460( 0*

0* )2317( ssJ DD

Backup


BaBar run 5


Inner Tracking and Vertexing: SVT

• Extrapolation of secondary vertex

• Standalone tracking capability for low pt tracks

Double side silicon microstrips

layers resolution (m)

1-3 10-15

4-5 40

High pT track

Low pT track


The Detector of Internal Reflected Cherenkov light

)βn1(cos)( 1Ec

A charged particle traversing the DIRC produces Cherenkov

light if n>1


Particle IDentification:dE/dx, DIRC

For tracks with p<700MeV: dE/dx from

DCH and SVT

For tracks with p>700MeV:

Cerenkov angle from DIRC


Photons: EMC

• Projective geometry

• Discriminate between hadron and electromagnetic showers

• Contribute to triggerm=134.5MeV

=6.4MeV

m (MeV)


Theoretical DsJ Interpretation References

• Cahn, Jackson: Phys.Rev.D68, 037502 (2003) • Lucha, Schoberl: Mod.Phys.Lett. A18, 2837 (2003)• Bardeen, Eichten, Hill: Phys.Rev.D68,054024 (2003)• Beveren, Rupp: Phys.Rev.Lett.91, 012003 (2003)• Bali: Phys.Rev.D68, 071501 (2003)• Dai, Huang, Liu, Zhu: Phys.Rev.D68,114011 (2003)• Szczepaniak: Phys.Lett.B567, 23(2003)• Browder, Pakvasa, Petrov: Phys.Lett.B578, 365 (2004)• Barnes, Close, Lipkin: Phys.Rev.D68,054006(2003)• Maiani, Piccinini, Polosa, Riquer: Phys.Rev.D71.014028

(2005)


Low energytrack efficiency

from slow


Reconstruction of Soft Pions• Fundamental to understand our capability of

reconstruct D*

• Estimate tracking efficiency from data itself

We reconstruct: D*+ D0 +

m = m(D*+)-m(D0)=140.6 MeV

m()=139.6 MeV Energy available for the is

very low

Expected symmetric angular distribution of the events in

the D* frameD* direction

of flight

Helicity angle

1 00

Angular analysis

JP K


Soft Pion studies

Separation of pion sample based on D* momentum

p(D*) GeV/c

)cosβ(γ *** ssspEE

For a given D* momentum:

linear relationship

Slow

er D*

Critical regions

p(D*) bins


Background subtraction• Use of two kinematic

variables: m(D0), m

• Four categories of events:

1. Signal

2. Real-D0+bad-s

3. Bad-D0+real-s

4. Combinatoric background

• Use of kaon and pion PID to distinguish between different contributions m

m(D

0 )

Background removal within each p(D*) bin, that cover the same soft pion kinematic range of the signal


Efficiency of Soft Pion

-1.0 1.00

Convolute the helicity distributions with an efficiency function parameterized as:

0

00

01)(

11

)(pp

ppppp

Low p(D*)

High p(D*)

cos(*)

)cos1(cos

*2*

Nd

d

Efficiency estimate from asymmetries in the helicity angle distributions

Asymmetric distribution

Expected distribution (symmetric)

Low cos()


Soft Pion Efficiency Results

• Convoluting function parameters obtained minimizing a 2

• Relative efficiency raise over 90% already at 100Mev/c

• From the differences between data and simulation: a systematic uncertainty of 1.4% per track in the efficiency

SimulationData

DataSimulatio

n

170 ± 7 148 ± 16

p0 65.5 ± 0.2 65.0 ± 0.4

p() GeV/c

Efficiency


Event Selection (I): tracks

“very loose” 50MeV<p<10GeV d0<1.5cm |z0|<10cm

Tracks:

Kaon PID:

Photons and 0:

“loose”E()>30Me

VLAT<0.8

115<m()<150MeV

Invariant mass:

“not a pion” PID and p(K)>250MeV

use dE/dxefficiency

95%mis-id<20%

“loose” 1005<m()<1020 MeV helicity cut |cos(h)|>0.3

221

221 ||)( ppEEm


Event Selection (II): D0, Ds

m0 (MeV) (MeV) n cut other modes

D0 1863.1 6.3 3 K0,KDs 1966.1 5.3 3 K*K

Measure invariant mass m, and resolution in data:

Apply the request: - n < m-m0 < n


Another example

• B0->D*-DsJ(2460)+, DsJ->Ds*pi0– We have D*->D0pi

(soft +)

– Ds*->Dsgamma

– D0,Ds as before

• Pi0 veto on gamma

tight PIDand p>250MeV

use DIRC for p>0.6GeV

efficiency 85% mis-id<5%


Gev/c2

Background from BD(*)Ds(*)

• Identical D(*),Ds(*) selection

• B candidates selected in mES, E signal region

Events rejected

Eve

nts/

10 M

eV/c

2

200

02.0 2.7

m(Ds)

2.35

Reject events with at least a candidate

compatible with BD(*)Ds

(*)

Background events that enter marginally in the DsJ signal region

easily combine with low energy or 0 to

give a DsJ

350


Gev/c2

Ent

ries

/10

Mev

/c2

Background Events

• Simulated ~220 fb-1 of generic events– No peaking background

observed

m(Ds0)

Gev/c2 2.62.2 2.4

Ent

ries

/10

Mev

/c2

50

100

m(Ds0)

2.62.2 2.4

200

400• Simulated ~60k events

for each mode BD(*)Ds(*)

– No peaking background observed


Reconstruct B candidates

B candidates must enter in the signal box: mES, E

Determine selection criteria using a simulation60k signal

events for each submode

Resolution:=16 MeV

If more than one B candidate is found, the one with the smaller difference E-E0 is retained

E

GeV

Eve

nts/

5 M

eV/c

2

10000

5000


nisig = 32.7±10.8

nisig = 34.8±7.9

nisig = 15.3±6.8

nisig = 23.6±6.1

s=3.1

s=5.5

s=5.2

s=2.5


nisig = 28.0±5.8

nisig = 17.4±5.1

nisig = 30.5±6.4

nisig = 26.5±5.6

s=5.1

s=4.2

s=7.4

s=7.7


nisig = 32.0±8.2

nisig = 24.8±6.5

nisig = 34.6±7.5

nisig = 53.0±7.7

s=4.3

s=5.0

s=11.7

s=6.0


Other Efficiency and Cross-feed

• In B+D0DsJ(2317)+ cross-feed is dominated by DK D0K0

D0 K0

D K reconstructed as D0 K0

m(DsJ)m(DsJ)

GeV/c2 GeV/c2

250

10

Efficiency Cross-feed

i=(1.93±0.06)% fij=(0.04±0.01)%

nisim = 1160 , gi=60000 nij

sim = 24 , gj=60000


Isospin averaged branching ratios

• Combine D+ and D0 and D*+ and D*0

measurements

• Average with statistical weight w=1/i2

• To compare two measurements x1 and x2 with variance 1 and 2 we use the variable z:

n

iii Bw

wΒ

1

1

22

21

21

xxz


Ratios of Branching Ratios

• Compare BD(*)Ds and BD(*)DsJ measurements is possible through ratios:

• Neglecting phase space we expect:

• We know BD(*)Ds from PDG (1-5%)

• Final results to be revised

)(

)( 00

s

sD DDBBr

DDBBrR

)(

)(*1

1s

sD DDBBr

DDBBrR

)(

)(*

0*

0*s

sD DDBBr

DDBBrR

)(

)(**1

*

1*s

sD DDBBr

DDBBrR

Datta, O’donnell

Phys.Lett. B568:254,2003

110 DD RR and similarly for RD*0 and RD*1


Comparison with Belle

Decay channel BaBar Br(10-4) Belle Br(10-4) z

8.08.37.129.25.26.18][)2460(

1.09.18.04.69.03.17.6][)2460(

0.26.87.283.128.97.61][)2460(

2.14.48.146.43.56.27][)2460(

)5.8(1.32.22.39.12][)2317(

6.00.35.11.108.17.25.13][)2317(

2.20.2

4.69.3

**

4.24.1

*

4.74.6

9.209.12

0***

8.25.2

4.98.5

0**

1.27.1

4.47.2

0**

7.49.2

0*

ssJ

ssJ

ssJ

ssJ

ssJ

ssJ

DDDB

DDDB

DDDB

DDDB

DDDB

DDDB

Phys.Rev.Lett.93, 181801 (2004)

J.Phys.Conf.Ser.9:115-118,2005


Comparison with old Belle resultsPhys.Rev.Lett.91:

262002,2003

Experimental results

compatible within errors


Conclusions

“no compelling evidence that a non-standard scenario is required … neverthless unanswered questions remain …” (Review by P.Colangelo, F.De Fazio, R.Ferrandes, hep-ph/0407137)

hadronic b decays to double-charm final states

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