Gianluca Cavoto1

Measurements of and sin(2) in BaBar

Gianluca CavotoPrinceton University

Università di Roma ‘La Sapienza’On behalf of the

BaBar Collaboration

ICHEP'04 32nd International Conference on

High Energy Physics

Gianluca Cavoto2

Angle of the Unitarity TriangleMeasure relative phase between Vub and Vcb

from direct CP asymmetry

Process mediated by both b c and b u amplitudes

Results (all preliminary)

0

(*)

(*)0 0

0 *0 0 0

0

*

, (

[ 3

)

[ ]

]

CP

CP

CPB D K D D K

B

B D K

D K

B D D body

K

K

0 (*)

(*)

0

00 (*)0

,

s

D

Search fo

B D

B D

D

K

r B

sin(2+) time dependent CP asymmetry

Updated and new results

Gianluca Cavoto3

from direct CP violation

Relative size (rB) of B decay amplitudes

Different incarnations…

Not well constrained by theory.Larger rB, larger interference, better experimental precision

Relative strong phase (B) unknown

( )( )B

A b urA b c

Interference when D final state common to both D0 and D0

BaBar hep-ex/0402024 0.22(90% . .)Br C LBelle hep-ex/0406067

0.100.140.26 0.03 0.04Br

Bi ie e

Gianluca Cavoto4

Gronau London Wyler method

CP modes: small D0 branching ratio

D decays into CP eigenstate

Select CP-even and CP-odd final states

Theoreticallyclean, but with 8-foldambiguity

0 02

0

( ) ( ) 1 2 cos cos2 ( )CP CP

CP B B BB D K B D KR r r

B D K

0 0

0 0

( ) ( ) 2 sin sin( ) ( )

CP CPCP B B CP

CP CP

B D K B D KA r RB D K B D K

3 observables, 3 unknowns

2)(000 DDDCP

Normalize to D0 decay into flavour state (K-+)Experimentally

Gianluca Cavoto5

Analysis techniques

Cerenkov angle No charge confusion. Clear separation D/D

BF(B DK) ~ 10 -4, BF(D f) ~ 10 -2 reconstruct as many f final states as possible

dataMC

High reconstruction efficiency

Reject

eventstopological variables

in Neural Network or Fisher discriminant

e e qq

2*2*BbeamES pEm

**beamB EEE

Gianluca Cavoto6

B-D0CP- yields

D0 background

B+ CP+ B- CP+ B- CP-B+ CP-

NBB=214 106

Combine severalfinal states

NBB=227 106

75 13

18 7

K K

0 76 13SK

15.1 5.8CP 34.4 6.9CP

Adding KS, KS

D0CP K - CP+ (+-,K+K-) CP- (KS0)

D0CP K* - (K* - KS-)

Gianluca Cavoto7

GLW B-D(*)0CP*)- results

CP

CP

- 0.80 0.14 0.08

0.21 0.17

0.87 0.14 0.06

0.40 0.15 08

0

0

.

.

07C

C

P

P

R

R

A

A

D0CP K - D0

CP K* - (K*- KS-)

0.040.1CP- 4

CP

0.33 ( 1.15 0.0.34 0.1 )0 12 ( )

0.76 0.29 0.0

1.77 0.37 0.12

0.09 0.20 0.0

6

6

CP CP CP

CP

A AA

R

A

R

Additional systematic erroron ACP- ( CP even background)

More CP eigenstate final states still to be added…

More statistics needed to constrain

Loose bound on rB22(1 )CP CP BR R r

From DCPK*2 0.23 0.24Br

0.100.081.09 0.26

0.02 0.24 0.05CP

CP

RA

D*0 (D0CP0)K -

NBB=214 106 NBB=227 106

NBB=123 106

Gianluca Cavoto8

Atwood Dunietz Soni method

0

0

| ( ) | 0.060 0.003| ( ) |DA D KA D

rK

Input:

Count B candidates with opposite sign kaons

2 2([ ] ) ([ ] ) 2 cos( ) cos([ ] ) ([ ] )ADS D B B D D B

Br K K Br K KR r r r rBr K K Br K K

([ ] ) ([ ] ) 2 sin( )sin /([ ] ) ([ ] )ADS B D D B ADS

Br K K Br K KA r r RBr K K Br K K

D decay into flavor state

Phys.Rev.Lett.91:171801,2003

B D

D decay strong phase D unknown

Gianluca Cavoto9

ADS results

D0K D*0(D00)K D*0(D0)K

1.30.8

2.

4.0.

1.4

2

1

3

*( )

*( )

([

([ ] )

] ) 0.2

([

.

)

7

] 1.2

4D

D D

D D

N K K

N

N

K

K

K

K

NBB=227 106

No signal in current dataset

Gianluca Cavoto10

rB from ADS method

RADS R*ADS

0.030 (90%CL)ADSR * 0.021 (90%CL)ADSR

0.23 (90% )Br CL * 0.21 (90% )Br CL

No AADS measurement

1

48 73

D

D

o o

anyr

any

D0K D*0(D00)K D*0(D0)K

Sensitive to rB (RADS~r2B)

Not easy to determine

Gianluca Cavoto11

B- D(*)0 - D0(S) Dalitz analysis

=75,=180,rB=0.125

Isobar model for f(m2+ ,m2

- )can fix phase variationD across Dalitz plot.

Only two-fold ambiguity in extraction

Sensitivity to

Amplitude for B-/B+ “D0”K-/K+

202 )( SKMm

202 )( SKMm

If we knew the charm phase shift D?

DCS K*(892)

(770)

Gianluca Cavoto12

D0(S) Dalitz model

Plot of mpipi

Determined on D* D0 sample

No D-mixing, No CP violation in D decays

(770)

CA K*(892)

DCS K*(892)

2m

2m2m

Gianluca Cavoto13

B-D0-, B-D*0-

261 19

83 11

40 8Dalitz projection for mES >5.272 GeV/c2

Signal plus backgroundPDF superimposed

NBB=211 106

B+ B+

B- B-

0B D K

DCS K*(892)

DCS K*(892)

D0K

D*0(D00)K

D*0(D0)K

2m

2m2m

2m

Gianluca Cavoto14

from B-D(*)0[S]

With current statistics, no rB sensitivity for rB<0.10

0.18 (90% )Br CL * 0.24 (90% )Br CL

Bayesian confidence regions

D0K-

68%

95%

D*0K-

D0K- D*0K-

* (311 52 23 10)oB

(88 41 19 10)o Dalitz model syst

180

-180

0

180

0

0.3

0.3

r*B

(130 45 8 10)oB

rB-180

0.3 0.30. 0.

A posteriori rB(rB*) with uniform a priori

Gianluca Cavoto15

Critical rB…

rB

D0 Dalitz

(

) measurement fromcombination of many modes(multiple constraints on rB)

rB =0.1

rB =0.2

rB =0.3

, 13062 , 15o oB D

o

0 90 180

GLW only ADS only (D and Bunknown)GLW+ADS

sensitivity projection for 500 fb-1

2

0.23 (90% )Br CLFrom ADS

211

ADS B

D

B

A SB

R rA Ar

R r

GLW ADS

= 62o

Gianluca Cavoto16

sin(2+) with B0 D(*)-+/+ Time dependent CP analysis

favored bc amplitude suppressed bu amplitude

|||| *1 udcbVVA

time-dependent CP violation arises from interference of mixing and decay:

0B0

B

(*)D

iicdub eeVVA |||| *

2

2

b u

dc

dd0

B

*DubV

*cdVu

d

dd0B *D

*cbV

udV

b c

The final state is accessible from both B0 and B0

Exclusive reconstruction of D-+, D*-+,D-+

Partial reconstruction of D*-+

D*Combinatoric BBPeaking BB Continuum

Lepton tag

*0 DBsoftD

0

X

Asymmetry parameters

2 sin(2 )cos

2 cos(2 )sinlep

a r

c r

~ ~

Gianluca Cavoto17

B0 D(*)0(*)0

(*)0 00

00 (*)0

( )

( )

B D KrB D K

Sensitivity given by

0 *00 ( )B D K K

Search for b u transition(self tagging mode)

Eventually TD analysis…

No signal…

NBB=124 106

0 0 *0 5( ) 4.110 90% . .BR B D K at C L

Gianluca Cavoto18

Unitarity triangle constraintsConfidence regions in plane

Combination of BaBar a and c results with uniform prior in r

Search for B0 DsImprove bound using SU(3) r from B0D+

s-

3( ) 9.5 10 90% . .r D at C L

Not encouraging for D…

http://www.utfit.org

NBB=90 106

.

68% C.L. 95% C.L.

(*)

(*)

0 (*)(*)

0 (*)

( )tan( )

S

S DC

D

fBR B DrBR B D f

Phys.Rev.Lett.90:181803,2003

* 0.0050.007

0.019 0.004

0.017

r

r

hep-ph/0408079

Gianluca Cavoto19

– More modes and techniques added to measure GLW, ADS, D0K Dalitz, time-dep. sin(2+)

– No single golden technique– Constraints on b u amplitude in B DK

Evidence for small rB

– Sensitivity to relies heavily on rB

from combination of many modes

Combination of BaBar GLW+ADS+D0K Dalitz

Conclusion

68 %C.L.

( )( )B

A b urA b c

95 % C.L.

Gianluca Cavoto20

Backup slides

Gianluca Cavoto21

sin(2+): results

Exclusive reconstruction of D-+, D*-+,D-+

Higher resonance Included in syst.error

- higher signal purity, lower efficiency

Partial reconstruction of D*-+

- high efficiency, more background

NBB=110 106

NBB=178 106

*

:

: , ,1 ( )

i flavor tag category

D D Dflavor