Gianluca Cavoto1

Measurements of and sin(2 ) in BaBar

Gianluca CavotoPrinceton University

Università di Roma La Sapienza

On behalf of theBaBar Collaboration

ICHEP'0432nd International Conference on

High Energy Physics

Gianluca Cavoto2

Angle of t he Unit arit y Triangle

Measure relative phase between Vub and VcbMeasure 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

f rom direct CP violat ion

Relative size (rB) of B decay amplitudes

Different incarnationsDifferent incarnations

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

Relative strong phase ( B) unknown

( )

( )B

A b ur

A b c

Interference when D final state common to both D0 and D0Interference 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 D decays into CP eigenstate

Select CP-even and CP-odd final states

Theoreticallyclean, but with 8-foldambiguity

0 02

0

( ) ( )1 2 cos cos

2 ( )CP CP

CP B B B

B D K B D KR r r

B D K

0 0

0 0

( ) ( )2 sin sin

( ) ( )CP CP

CP B B CPCP CP

B D K B D KA r R

B D K B D K

3 observables, 3 unknowns

2)(000 DDDCP

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

Gianluca Cavoto5

Analysis t echniques

Cerenkov angleNo charge confusion. Clear separation D /D

BF(B DK) ~ 10 -4, BF(D f) ~ 10 -2 reconstruct as many f final states as possible 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 5.8CP34.4 6.9CP

Adding KS , KS

D0CP K -D0

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

D0CP K* - (K* - KS

-)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 - D0CP K* - (K*- KS

-)D0CP 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 finalstates still to be added More statistics needed to constrain 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

R

A

D*0 (D0CP

0)K -D*0 (D0CP

0)K -

NBB=214 106 NBB=227 106

NBB=123 106

Gianluca Cavoto8

Atwood Duniet z Soni method

0

0

| ( ) |0.060 0.003

| ( ) |D

A D K

A Dr

KInput:

Count B candidates with opposite sign kaons 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 r

Br K K Br K K

([ ] ) ([ ] )2 sin( )sin /

([ ] ) ([ ] )ADS B D D B ADS

Br K K Br K KA r r R

Br K K Br K K

D decay into flavor stateD 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(D0 0)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

KNBB=227 106

No signal in current datasetNo signal in current dataset

Gianluca Cavoto10

rB f rom 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

any

r

any

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

Sensitive to rB (RADS~r2B)

Not easy to determine Not easy to determine

Gianluca Cavoto11

B- D(*)0 - D0( S ) Dalit z analysis

=75, =180,rB=0.125

Isobar model for f(m2+ ,m2

- )can fix phase variation

D across Dalitz plot.

Only two-fold ambiguity in extraction

Sensitivity to

Amplitude for B-/B+ D0 K-/K+Amplitude for B-/B+ D0 K-/K+

202 )( SKMm202 )( SKMm

If we knew the charm phase shift D?If we knew the charm phase shift D?

DCS K*(892)

(770)

Gianluca Cavoto12

D0( S ) Dalit z model

Plot of mpipi

Determined on D* D0 sampleDetermined on D* D0 sample

No D-mixing, No CP violation in D decays

(770)

CA K*(892)

DCSK*(892)

2m

2m 2m

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(D0 0)K

D*0(D0 )K

2m

2m 2m

2m

Gianluca Cavoto14

f rom B- D(*)0[ S ]

With current statistics, no rB sensitivity for rB<0.10 With current statistics, no rB sensitivity for rB<0.10

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

Bayesianconfidence regions

Bayesianconfidence 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

Crit ical rB

rB

D0 Dalitz

measurement fromcombination of many modes(multiple constraints on rB)

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

21

1ADS B

D

B

A SB

R r

A Ar

R rGLW ADS

= 62o

Gianluca Cavoto16

sin(2 + ) with B0 D(* )- +/ +

Time dependent CP analysisTime dependent CP analysis

favored b c amplitude suppressed b u 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 BBContinuum

Lepton tag

*0 DB

softD0

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 Kr

B 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

Unit arit y t riangle const raints

Confidence regions in planeConfidence regions in plane

Combination of BaBar a and c results with uniformprior in r

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

s-

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

Not encouraging for D

http://www.utfit.orghttp://www.utfit.org

NBB=90 106

.

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

(*)

(*)

0 (*)(*)

0 (*)

( )tan

( )S

S DC

D

fBR B Dr

BR 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 measureGLW, ADS, D0K Dalitz, time-dep. sin(2 + )

No single golden technique

Constraints on b u amplitude in B DKEvidence 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 ur

A 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 D

flavor

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