From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 ·...

23
BELLE From — Status and Prospects Tim Gershon IPNS, KEK Workshop on the CKM Unitarity Triangle April 6, 2003 Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

Transcript of From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 ·...

Page 1: From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 · VudVub * VcdVcb * V ... Tim Gershon Workshop on the CKM Unitarity Triangle April

BELLE

��

� From — Status and Prospects

Tim GershonIPNS, KEK

Workshop on the CKM Unitarity TriangleApril 6, 2003

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

Page 2: From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 · VudVub * VcdVcb * V ... Tim Gershon Workshop on the CKM Unitarity Triangle April

BELLE Introduction

� ��� �� � �� � � �� � � �

(0,0) (1,0)

(ρ,η)

φ1

φ2φ3

VudVub*

VcdVcb*

VtdVtb*

VcdVcb*

� Require interference between

� �� &

� �� processes� � � ��

is a good place to look– Relatively abundant processes with relatively clean signals� So what is the problem?– Smallness of

� �� amplitude relative to

� ��

– Efficiency to reconstruct

� So what is the solution?� Measure

� �� �� � �! " �$#% & ' ' at

�factories, so why not

� �)( �* �� ! " �#+ , ' ' ?Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

Page 3: From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 · VudVub * VcdVcb * V ... Tim Gershon Workshop on the CKM Unitarity Triangle April

BELLE Notation & Disclaimers

As is common in

physics, different notations exist in the literatureI will use ��� Amplitude to a

specific final state,

� � Rate to a

specific final state,

Direct CP asymmetry,

� � ��� � � �� �

�� � � �� �

Branching fraction,

� � �� � � � �

Ratio of suppressed to favoured amplitudes

Disclaimers

� I apologise in advance for any bias towards Belle &

-factories

� All results are preliminary unless you can find them in a journal

� Not enough space to give references � � � sorry!

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

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BELLE The GLW Method

Access

� ��� �� via interference between

� � � � � �

&

� � � � � � �

by reconstructing

decays to

��

eigenstates

�� (

��

even) &

� � ( ��odd)

� � � � �� ��� � � � � � � � �� ��� � �s

b

u

c

uW

uu

u

c

s

b

u

W

s

b

u

c

uW

uu

u

c

s

b

u

W

COLOUR ALLOWED COLOUR SUPPRESSED

K−)

D0K−)

0

φφ

δ

δ3

3

(B− DCP2A

(B−

(B− D K−)

A

A

����� �� � ���� �� � ! " #� �� $ � ! "% &(' )+* $, - �.� �� / - � �� �� 01 � "#� �� $ 01 � "% &(' )+* $ � � / �� � 2 � ��� �� � ! "#� �� $ � ! "% &(' )+* $, - �.� �� / 2 � �.� �� 01 � "#� �� $ 01 � "% &(' )+* $

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

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BELLE Problems With The GLW Method

� ��� ��� is small, early predictions of� ��

� � � observation of COLOUR SUPPRESSED

� � � ��� �

, etc. (Belle, BaBar, CLEO)

� � � � � ��

(?)

� Hard to measure

� � � � since

� � � � � �� � � � � � � �� �

� � � � � � � � � �

instead measure

� � � �� ��� � � ��� � � � � �� � �� � � ��� � � � � �

� ��� � � � � � � �� � �� � � � � � � �

where

� �

indicates the

is reconstructed in a “flavour-specific” mode

��� � � � !"# $ �% !"# &'( )* !"# + &'( ), -/. 021 + � $ � � � !"# $43 % !"# &'( )* !"# + &'( ), -. 021 +

� Measure

� �5� ��� ,

� � � ��� ,� ,� �, note that

� �5� ��� � � �� � � � � � �

3 independent measurements & 3 unknowns (

� � � � ,

6 � � � ,

� ��� �� )

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

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BELLE

� � � �� Results - BaBar

� BaBar have studied

� � � �

with� �� �� �

(� �� �

with� � � � � �

No

�� identification

-id required

(GeV)KE∆-0.1 -0.05 0 0.05 0.1

Eve

nts/

0.00

58 G

eV

0

20

40

60

80

100

120K0 D→B

π0 D→B

bkg

BABAR

(GeV)KE∆-0.1 -0.05 0 0.05 0.1

Eve

nts/

0.01

15 G

eV

0

5

10

15

20

25K0 D→B

π0 D→B

bkg

BABAR

� �

�� � � � ���� � � �� � � � �� � ��� ��� � ��

� � � ��

� � � ��� � �

NB.

peak around

, � peak around

� � � ��� �

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

Page 7: From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 · VudVub * VcdVcb * V ... Tim Gershon Workshop on the CKM Unitarity Triangle April

BELLE

� � � �� Results - Belle

� Belle have updated results using� � � � � �

for� � � ��� � � � �

;

� � � �� �� � �� � �� � �� � � �

� � � � � � � � � �

��

∆E (GeV)

Even

ts / 1

0 MeV

∆E (GeV)

Even

ts / 1

0 MeV

� �

∆E (GeV)

Even

ts / 1

0 MeV

∆E (GeV)

Even

ts / 1

0 MeV

�� �

∆E (GeV)

Even

ts / 1

0 MeV

∆E (GeV)

Even

ts / 1

0 MeV

��� � ��� � � �� � �� �� � ��

��� � ��� � � �� � �� �� � � �

� �"! #$ % &')( ' * + ')( ,- + ')( ' .

�/�"0 #1$ %32 ' ( ,4 + ')( ,5 + ')( ' 6

NB.

7

peak around 8 � � 93: ;

,

< peak around

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

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BELLE Extensions and Alternatives to the GLW Method

� � � � � � �

� � � � � � �� � � �

measured by CLEO, Belle

– Belle:

� � �

events with

� � � � � �

in� � � � � � (cf.

�� � � � � � � � � �

with

� � � � � �

in� � � � � � )

� � � � � � (non-resonant)– both amplitudes colour allowed � large

� � � �– non-resonant branching fraction not yet observed

u

cbs

uu

u

u u

bs

u

u

u

c

u

� � � � � � Dalitz plot analysis– General extension of above– Beneficial if different contributions interfere

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

Page 9: From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 · VudVub * VcdVcb * V ... Tim Gershon Workshop on the CKM Unitarity Triangle April

BELLE More Extensions and Alternatives to the GLW Method

� ADS method– Use interference between

� � � � � � �

&

� � � � � �

� � � � � � � � � �SUPPRESSED

FAVOURED FAVOURED

SUPPRESSED

– Comparable amplitudes � � � large

– Product branching fractions become very small (below

� � �

)

� � � � � � � � � � �

– both amplitudes colour suppressed � � � large�

s

b

d

c

uW

dd

u

c

s

b

d

Ws

b

d

c

uW

dd

u

c

s

b

d

W

– These modes observed by Belle–

� � � � � � �

tags flavour of

� do not need flavour tagging– Can also study time-dependence � � � more later

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

Page 10: From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 · VudVub * VcdVcb * V ... Tim Gershon Workshop on the CKM Unitarity Triangle April

BELLE

� � � � � � ��� � �

Results - Belle

Results with

� � � � �

0

5

10

15

20 D0K-0

0

10

20

-0.2 -0.1 0 0.1 0.2

D0K-*0

∆E (GeV)

Events/(0.01 GeV) 0

5

D*0K−0

0

5

10 D*0K−*0

0

20D−0K−*0

0

10

−0.2 −0.1 0 0.1 0.2

D−*0

K−*0

∆E (GeV)

Events/(0.01 GeV)

� ��� � � � � � � � � ��� � �� �

� � � � �� � �

� ��� � � � � � � � � � �� � � ��

� � � � �� � �

� ��� � � � � � � � � � � � � � � �

� ��� � � � � � � � � � � � � � � � �

� ��� � � � � � � � � � � � � � � �

� ��� � � � � � � � � � � � � � � � � �

If

��� �� � is large, hope to see hints for

� � � � � � � � � �

soon

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

Page 11: From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 · VudVub * VcdVcb * V ... Tim Gershon Workshop on the CKM Unitarity Triangle April

BELLE Yet Another Extension of the GLW Method

� Consider

� � � � �

with

� � �� � � �

� �� �� �

Dalitz plot has contributions from:

� � � � � � � � � � � � � � � � �� �

� � � � � � � � � � � � � � � � � � �� �

� � � � �� � � � � � ��

�� � � � � �

� � � � � �� � � � � � � ��

�� � � � � �

� � � and many other possible modes

� Study

�� � � �

Dalitz plots for

� � � � �&

� � � � �

� � � enough information to extract

� � � �� cleanly

� Can use other multibody final states of

�decay

� Can do the same for

� � � � � � � � � �

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

Page 12: From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 · VudVub * VcdVcb * V ... Tim Gershon Workshop on the CKM Unitarity Triangle April

BELLE

� � � ��

� �

Dalitz Plot Analysis - CLEO

Note that

� � �� � � �

Dalitz plot analysis has been done by CLEO

� NOT from�

decay!

� 5299 candidates

� �

� �background

� “wrong-sign”

� � � � � � �

observed (

� � � � significance)� “

”� ��

� � � �

error on the phase difference

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

Page 13: From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 · VudVub * VcdVcb * V ... Tim Gershon Workshop on the CKM Unitarity Triangle April

BELLE Time-dependent

� � � � �

� Note that in any mode discussed so far, can replace � � �

&

� �

becomes

� � � � �� � � usually not worth considering

� BUT let’s make an exception for

� � � � � (no

� � equivalent)

d

b-

d

c-

u

d-

B0

D*-

π+

VcbVud

� favoured �

d-

b

d-

c

u-

d

B0-

D*+

π-

VcbVud

d

b-

d

u-

d-

c

B0

π-

D*+

VubVcd

� suppressed �

d-

b

d-

u

d

c-

B0-

π+

D*-

VubVcd

� Time evolution: (

��� � � �� � � � � � �� )

�� � � �� � � ���� � � ��� �� � � ���� � ! � � " � �� � ! � � "$#% &�' (' ) " � � � � & *,+ �- . � / � � " & * + �' (' ) "0

�21� ,� � �� � � ���� � � ��� �� � � �3�� � ! � � " � �� � ! � � "$#% &�' (' ) " � � � � & *,+ �- . � / � � " & *,+ �' (' ) "0

�4� ,� � �� � � ���� � � ��� �� � � ���� � ! � � " � �� � ! � � " #% &�' (' ) " � � � � & *,+ �- . � / � � " & *,+ �' (' ) "0

�21� � � �� � � � ��� � � ��� �� � � �3�� � ! � � " � �� � ! � � "$#% &�' (' ) " � � � � & *,+ �- . � / � � " & * + �' (' ) "0

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

Page 14: From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 · VudVub * VcdVcb * V ... Tim Gershon Workshop on the CKM Unitarity Triangle April

BELLE

� � � � � � �� �� � ��� �� �

Time-dependent

� � � analysis accesses � ��� � � �� � � � ��� �� �

� � � since � ��� � � �� � �

is measured � � � � ��

BUT precise measurement of � ��� � � �� � � � � � �� �

may not precise� ��� ��

Take � ��� � � �� � � � �� ��

– measure � ��� � � �� � � � � � �� � ��

� � � � ��� �� � � �

On the other hand– measure � ��� � � �� � � � � � �� � ��

�� � �

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

Page 15: From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 · VudVub * VcdVcb * V ... Tim Gershon Workshop on the CKM Unitarity Triangle April

BELLE

� � � �

�� � ����������� �� � � � �� � � ���������� �

��

� Cannot extract

� � � � from

� � � data

� Clean measurement in principle from

� � � � � � � � � � � � � � � � � �

� Instead use

� � � � � ��� � �

� � � � � � � ��� � � � �� � � � � � � � � � � �

� � � � �

��

� ������ � � ��

� � ���� �

� BaBar and Belle have measured

� � "! # $ %&(' ) * +

, , , limiting systematic is

� - % *' $ . ) *0/

� Belle has measured

� - % *' $ . ) *1/

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

Page 16: From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 · VudVub * VcdVcb * V ... Tim Gershon Workshop on the CKM Unitarity Triangle April

BELLE

��� � � ���� �

Both BaBar and Belle also measure

! $ % ' �

(not relevant to this discussion)B

aBar

Even

ts/2

0 M

eV B0→Ds+π-

Data

MDssidebandsCombinatorial

charmless

B0→D-π+

B0→D-ρ+

∆E(GeV)

B0→Ds-K+

0

5

10

15

012

-0.25 0

0

2.5

5

7.5

10

-0.2 -0.1 0 0.1 0.2

Bel

le 0

2

4

6

8

10 Ds+K-

0

2

4

6

-0.2 -0.1 0 0.1 0.2

Ds+π-

∆E (GeV)

Events/(0.01 GeV)

���� ��� ���� � � ��� � ���� � �� � ���� "! # $ #! # # $ #! � %� #� &

� �� �� ��'� � � �� � ��'� � �� � ��� #! () � � *+� � * � $ #! + � #� &

Belle measures

� � %&�' $ . )& +-, ./0 0 12 3 45 67 1 / 378 459 : 178 :0 12 3 45 6 7 1 / 378 45

5.200 5.225 5.250 5.275 5.3000

20

40

60

Mbc(GeV)

#entry

/2.5M

eV

0

200

400

600

800

1000

1200

1400

1600

1800

1.86 1.88 1.9 1.92 1.94 1.96 1.98 2 2.02 2.04 2.06

#event

/2MeV

Mmiss GeV

rejectreject

side band side band

� � %&�' $ . )& +, �<; , = > ? � , ;@ * #! AB& #! # C +ED F � & � G � �� � H � , � > > ? � , � � =

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

Page 17: From — Status and Prospects Tim Gershonbozzi/IFAE2003/CKM2003/gershon_4_06.pdf · 2003-04-12 · VudVub * VcdVcb * V ... Tim Gershon Workshop on the CKM Unitarity Triangle April

BELLE

� � Analysis Techniques

Method Usage Pro ConFull reconstruction BaBar & Belle �� &

��� Good

� ��

Low efficiencyPartial reconstruction, any tag BaBar �� Very large statistics Poor

� ��

Partial reconstruction, lepton tag Belle

��� Large statistics, clean tag Poor

� ��

)2

Missing Mass (GeV/c1.8 1.81 1.82 1.83 1.84 1.85 1.86 1.87 1.88

)2Ev

ents

/(2 M

eV/c

0

500

1000

1500

2000

2500

3000

)2

Missing Mass (GeV/c1.8 1.81 1.82 1.83 1.84 1.85 1.86 1.87 1.88

)2Ev

ents

/(2 M

eV/c

0

500

1000

1500

2000

2500

3000

Decay Time Difference (ps)

BaBar

−15 −10 −5 0 5 10 15

Even

ts/(0

.8 p

s)

1

10

102

103

Decay Time Difference (ps)−15 −10 −5 0 5 10 15

Even

ts/(0

.8 p

s)

1

10

102

103

1.78 1.80 1.82 1.84 1.86

D0 missing mass (GeV/c 2)

0

200

400

600

800

1000

1200

Entri

es/0.

0021

GeV

/c2

DATAFitUn−peaked BackgroundPeaked Background

Belle

−0.2

0

0.2

0.4

0.6

0.8

1

−1500 −1000 −500 0 500 1000 1500

∆z (µm)A(∆

z)

� � � �

,

�� �� � � �

events

��� � ��� � �� � � � � �� � � � � � � � !

"� � � �

,

"� "� �# �

events

$&% � � � �� ' � � � � �( � � � � )� � ! * +

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

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BELLE

� � � � � � -� /F � -�� /;

- Monte Carlo Studies

Can generate Monte Carlo with any

� ��� ,

��� , � �� - > . �� % � . ��� %# /

using EvtGen

This example uses

� partial reconstruction

� lepton tag

� � � �� �� � �

sample

INPUT MEASURED�� ��� � �! � � � "# $ * � "&% $* * ' ��� % & #! #) ( & #! #) ( $ #! # B

� � ��� � �! � � � "# $ * � "&% $* & ' ��� % & #! # (( & #! # C # $ #! # )

) Asymmetric peaks in same flavour modes ) Shifted means of mixing asymmetry

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

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BELLE

� � � � � � -� /F � -�� /;

- Experimental Considerations

� High precision vertexing requiredshift in

��� of � F�� � $ shift in

> � ��� � �� - > . � � % � . �� %# ? ��� /

of � F

Partial reconstruction (lepton tag) very sensitive to charge dependencies

� Background contains

% ), % ��� % ,

% ��� %� , etc.$ same quark level process & same

violating effectPartial reconstruction techniques need sophisticated background treatment

� Kaon tags often come from

% � � % ), % � � % ,% ��� %� , etc.$ same

violating effect on the tag sideFull reconstruction & partial reconstruction (any tag) sensitive

� Different techniques are complementary

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

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BELLE

� , � - �/ �,

� - �/ � F

� Similar modes also access � �� - > . �� % � . ��� %# /

� % ), % ,

%� can only be studied using full reconstruction

� %� ,

%� � are

! $ � �

decays and contain extra information

– 3 helicity/transversity statesG ; ��� � �� ; �� � �, relative amplitudes & phases,

> . � � % � . ��� %#

– Total of 11 parameters$ can in principle be obtained from time-dependent angular analysis

– Interference between helicity amplitudes

� do not need to measure

� � � �– What is the best way to do this fit?

B

D*

D

π

ρ

π

π+

0

θθDρ

0

+

χ

*

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

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BELLE

� � � Polarization

� CLEO have measured

��� � �, � , � �� ? � , � F� ? � , � F >

��

���

? Can analyze

% � in same way as

% � ), replacing

> �� � � � �� - .� ? � �� / $ - > �� � F / > �� � � � �� - .� ? � � �/

– Complications if helicity states have different

� � � �,

� � �

– Beneficial for partial reconstruction where angular ( �) resolution may be poor

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

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BELLE

� � �/

� � � F Partial Reconstruction - BaBar

Large signal yields, but very large backgrounds

%�

)2

Missing Mass (GeV/c1.845 1.85 1.855 1.86 1.865 1.87 1.875

) 2

Eve

nts

/ (

0.00

12 G

eV/c

0

500

1000

1500

2000

2500

3000

a)

)2

) (GeV/c+π0πm(0.5 0.6 0.7 0.8 0.9 1

) 2

Eve

nts

/ (

0.02

48 G

eV/c

0

500

1000

1500

2000

2500

3000

b)

)2

) (GeV/c+π0πm(0.5 0.6 0.7 0.8 0.9 1

) 2

Eve

nts

/ (

0.02

48 G

eV/c

0

500

1000

1500

2000

2500

3000

Fisher Discriminant−4.5 −4 −3.5 −3 −2.5 −2 −1.5 −1 −0.5

Eve

nts

/ (

0.17

2 )

0

1000

2000

3000

4000

5000

c)

Fisher Discriminant−4.5 −4 −3.5 −3 −2.5 −2 −1.5 −1 −0.5

Eve

nts

/ (

0.17

2 )

0

1000

2000

3000

4000

5000

Decay Time Difference (ps)−15 −10 −5 0 5 10 15

Eve

nts

/ (

0.6

ps

)

1

10

102

103

Decay Time Difference (ps)−15 −10 −5 0 5 10 15

Eve

nts

/ (

0.6

ps

)

1

10

102

103

Decay Time Difference (ps)−15 −10 −5 0 5 10 15

Eve

nts

/ (

0.6

ps

)

1

10

102

103

d)

� > � � � & $ � � > � ? > � �events

�� �, F ,� F� ? � , �� � ? � , � =� � �

%� �

mmiss(Gev/c 2)

En

trie

s/(2

Mev

/c)

� > � � � & $ F � � � � ? F > � �

events

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003

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BELLE Prospects for

� -�� /; Measurement

Mode Summer 2003 (

F � � � � &

)

F � � � � � &

% �� �& � � � � � ��� � � , F >

,

� � � � , F �

Observe D

V (if

� � � �, �)

�� � � � � , �� $ . �� %# � ; � �

% �� #

Search for

"! # $ % # �� #

Search for

"! # $ % �� �� #

%� ) ' � � � � � � "# $ * � " % $* $ ' ��� % %�� #! ( - � �� - > . � � % � . ��� %# / / � � , F �

PARTIAL REC. Assume

� ��� &

' ��� known, may hit systematics limit%� ' � � � � � � "# $ * � " % $* $ ' ��� % %�� "! � - � �� - > . � � % � . ��� %# / / � � , ; �

PARTIAL REC. Worse than

�� � due to background, not

# # �

polarized% ��� % ) � ' � � � � � � "# $ * � " % $* $ ' ��� % %�� #! ( - � �� - > . � � % � . ��� %# / / � � , F �

FULL REC. All modes combined

� Dalitz plot & time-dependent angular analyses also look promising

� Clearly a long an arduous journey ahead of us to measure

. �� %#

� The first steps are being taken

, , , in some cases the path ahead is clear

, , , there may yet be surprises along the way

� Reason to be optimistic about prospects with

F � � � � � &

Tim Gershon Workshop on the CKM Unitarity Triangle April 6, 2003