Beauty 06, Oxford, 27 Sept. 2006 Marco Zito1 Measurements of gamma using ADS, GLW and other methods & future projections Marco Zito CEA-Saclay, Dapnia-SPP

Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 1

Measurements of gamma using ADS, GLW and other methods

& future projections

Marco ZitoCEA-Saclay, Dapnia-SPP

On behalf of the

BaBar and Belle Collaborations


Why measuring is difficult ?

VtdVtb*

VudVub*

VcdVcb*

In the Wolfenstein phase convention, is the angle between Vub and Vcb. The ratio Vub/Vcb enters all interference terms sensitive to : small asymmetry or few events !

Strategies : 1. γ : B->DK : (GLW) Small asymmetry : many modes

2. B->DK (ADS) Large asymmetry : few events 3. B->DK Dalitz plot analysis (previous talk)4. BD(*) Small asymmetry : partial + full reconstruction5. Other methods for measuring (2 β+γ)

(2β+γ)


with B D0K decays

Interference (and direct CP violation) may occur if D° and D° decay in the same final state f : f can be CP eigenstate (+-, K+K-, Ks° …) Gronau, London,

Wyler (GWL) method f =DCSD for D° (K+-) and CFD for D° (K+-) Atwood, Dunietz,

Soni (ADS) or f=3 body final state : Dalitz plot analysis (Giri, Grossman,

Soffer, Zupan) (previous talk)

B+

b

u

u

u

cs K+

D0

B+bu

cu

su

D0

K+Suppressed amplitude:

b u transitionColor suppression

Favored amplitude W

0

0

| ( ) |~ 0.2

| ( ) |

A B D Kr

A B D K

DCSD : Doubly Cabibbo Suppressed DecayCFD : Cabibbo Favoured Decay

0.1-0.2


The GLW Method & observables

R

r

KDBKDB

KDBKDBA

sinsin2

)()(

)()(

Ratio of Bf for CP/non CP

Asymmetry B-/B+ for CP=+1/-1

8 fold ambiguity on

Clean but statistically limited: Bf(B-→D0K-) Bf(D0 → CP) 10-6

R++R- =1+rB2

4 observables, 3 unknowns (r,δ,γ)

coscos21)()(

)()(2 2

00rr

KDBKDB

KDBKDBR

Study f=CP eigenstate

Weak sensitivity to r through


Measurement techniques (B D0K

Reconstruct B→D0h with D0→K[NON CP], D0 → K+K-, [CP+] and D0 →

K0s0 (K0

s,K0s) [CP-]

B →D0K B →D0

Eliminate background from qqbar/ccbar events using Neural Net or Fisher discriminants based on event shape variables

Fit of R(K/) based on kinematic variables (E) and PID

• For D(*)0K use Cancellation of many systematicsCancellation of many systematics

Excellent -K separation thanks to Dirc!


BaBar GLW results

D0K D0

148 CP-

PRD 73, 051105(R) (2006)

B→D0K131 CP+

A C P ¡ = ¡ 0:26§ 0:40§ 0:12A C P + = ¡ 0:08§ 0:19§ 0:08

R C P ¡ = 0:65§ 0:26§ 0:08R C P + = 1:96§ 0:40§ 0:11

B→D0K*PRD 72 (2005) 071103

B+ CP+

B- CP+

B+ CP-

B- CP- 14.8 B CP-

37.6 B CP+

RCP+ = 0.90±0.12±0.04RCP- = 0.86±0.10±0.05ACP+ = 0.35±0.13±0.04ACP- = -0.06±0.13±0.04

RCP+ = 1.96±0.40±0.11RCP- = 0.65±0.26±0.08ACP+ = -0.08±0.19±0.08ACP- = -0.26±0.40±0.12

232 106 BBS

R and A : functions of (r,δ,γ)


D0K

D*0

KD

0K

*

RCP and ACP World Averages

GLW measurements alone do not constraint 3. Information on and rB from combination with other methods. More statistics will help!GLW measurements alone do not constraint 3. Information on and rB from combination with other methods. More statistics will help!

CP

+C

P+

CP

+C

P-

CP

-C

P-

CP

+C

P-

CP

-C

P-

CP

+C

P+


with the ADS method

Small BF(~10-7), but A2 = O(A1): expect large CPV

B D

A1

A2

Combine dominant b→c transition with DCS D0 decayCombine dominant b→c transition with DCS D0 decay

Observables: Large sensitivity to rB

A (B-→[K+-]DK-) rBei(B-+rDe-iD

input:

Measure [K+-]K- and [K-+]K- rates


RADS=(0.0+8.4 -7.9±1.0)x10-3

hep-ex/0508048 386 106 B Bbar pairs hep-ex/0508048 386 106 B Bbar pairs

B-→D0K- ADS(Belle)

D0K

maximum interference (φ3=0, δ=180°):

rB<0.18 @ 90% C.L.

Despite larger statistics, suppressed channel not visible either:

Here too, more statistics will help!

RADS


BD(*)0K(*), DCS D0K+ decays

232 *106 BB pairsD(*)0K: PRD 72, 032004D0K*: PRD 72, 071104

events 34

KD0events 5 4

3

SKKD *0

mES (GeV/c2)

Eve

nts

Eve

nts

~no signal no constrain on (alone), only limits on RADS and rB (using |cos(B+D)cos|<1)

RADS rB

D0K <0.02990% C.L.

<0.23 90% C.L.

D*0K <0.023 (D*0D00) <0.045 (D*0D0)

90% C.L.<0.16

90% C.L.

D0K* 0.046±0.0321

0.20±0.14 1

rSB=

DK*, GLW+ADS combined


BD0K, DCS D0K+ 226 *106 BB pairsBABAR-CONF-06/007

Similar to previous analysis with f= K+. Complication for extraction from |AD|,D variation across the D0 Dalitz plane:

cos2 )][()][(

)][()][( 220DBDBADS rrrr

KfDBKfDB

KfDBKfDBKDBR

C

Compared to f=K+: more background but smaller rD

similar sensitivity to rB2 (limit from RADS using | Ccos | ≤ 1)

C A

D

rm A

D

rm cos

D

rm B d r

mA

D

rm 2

drm A

D

rm 2

drm

C unknown, |C|≤1rD2 (D0K)/ (D0K)| = (0.214±0.011)% (BaBar, preliminary)

N

sig18 15

18

Signal yield from fit

RADS<0.039(95% C.L.)

Experimental RADS likelihood

rB<0.185(95% C.L.)

Bayesian L(rB) (flat rB and |Ccos| prior PDFs)


Measurement of sin(2+) in B0D(*)

(*)

* i i iub cd rV V e A e e

CP violation from interference of mixing (weak phase= 2and decay (weak phase ) interference terms measures sin(2+)

Theoretically clean : no penguin contribution, strong phase measurable

Small time dependent asymmetry (o(4%)) r is an external input

Suppressed amplitudethrough

b u transition

d

bc

d

0B

u

*D

Favored amplitude

c0B

d

bu

d

*D

W W

Strong phasedifferenceCKM

angle

*cb udV V A

0 (*)(*)

(*) 0 (*)

( )( ) 0.02

( )

A B Dr D r

A B D

B0

B0

f

mixing


Experimental technique

(4s)

= 0.56

Tag B

z ~ 160 m Reco Bz ~ 80 m

z

K

D-

K+

+

K+

-

-

e- e+

B0 Time dependent analysis

Partial orFull reconstruction

D*-+ mixed

r = 0

r = 0.02 = 0sin(2+) = 1w=0

Unmixed D- +

Mixed D- +

Tag side CP violation effect


sin(2+) from B0D(*),D

aD= -0.010 0.023 0.007aD* = -0.040 0.023 0.010aD = -0.024 0.031 0.009

cD= -0.033 0.042 0.012cD* = +0.049 0.042 0.015cD = -0.098 0.055 0.018

Results from B0→ D(*), D full reco :

D+evts,

D*evts

D*evts

232 106 B Bbar232 106 B Bbar

PRD73 11101


Increase the statistics by reconstructing only the two pions

PRD 71, 112003[2005]

.)(013.0.)(020.0025.0

.)(009.0.)(014.0034.0*

*

syststatc

syststataDlep

D

- 18710 D* events tagged with a lepton- 70580 D* events tagged with a kaon

CP asymmetry

Most precise measurement to date

232 106 B Bbar232 106 B Bbar

B0D* partially reconstructed (BaBar)


sin(2φ1+φ3) (Belle)

(*)00 )( DBB *00 )( DBB

- full reconstruction 0* DD

D*π full rec

357 fb-1 ~ 392 106 B Bbar357 fb-1 ~ 392 106 B Bbar

PRD 73 092003 (2006)

S +(D*π)=0.049±0.020±0.011

S –(D*π)=0.031±0.019±0.011

S +(Dπ)=0.031±0.030±0.012

S –(Dπ)=0.068±0.029±0.012

Full+part-rec

Full-rec

CPV significance (S++S-): 2.5σ [D*], 2.2 [D]

S+ S+

S- S-

Full+part-rec


HFAG averages a and c parameters

a = 2r sin(2) cos () clept = 2 r cos(2) sin()a = 2r sin(2) cos () clept = 2 r cos(2) sin()

a = (-1)l(S++S-)/2 [belle]

c small DandD*small?More statistics will help! Individual measurements of a close to the 3 statistical significance!


Bf(B0 → Ds(*)

230 106 B Bbar230 106 B Bbar

N(Ds+-)=48

N(Ds*+-) = 42

Measure also

Ds→ , K0SK+, K*0K+

r(D) = (1.3 0.2 0.1 ) 10-2

r(D*) = (1.9 0.2 0.2 ) 10-2

W-exchange diagrams are small

hep-ex/0604012, submitted to PRL0B

d

u

*SD

bc

s

/

SU(3)

B(B°→Dsπ) = (1.3±0.3 ±0.2)x10-5

B(B°→D*sπ) = (2.8±0.6 ±0.5)x10-5

B(B°→DsK) = (2.5±0.4 ±0.4)x10-5

B(B°→D*sK) = (2.0±0.5 ±0.4)x10-5


Constraints in the ρ-η plane

Combine Babar and Belle, partial and fully reco results for the a and clep parameters and use the r parameters from SU(3) symmetry

r(D) = 0.013 ± 0.002r(D*) = 0.019 ± 0.003r(D) = 0.003 ± 0.006


b c amplitude ~ suppressed in B0→D(*)+a-0(2)

Potentially large CP-asymmetry

)2(0(*)0

)2(0(*)0

(*)

(*)

aDBAf

f

V

VaDBA s

D

D

cs

cd

s

fD= decay constant )2(0(*)0

)2(0(*)0

(*)

(*)

aDBAf

f

V

VaDBA s

D

D

cs

cd

s

B0→D(s)(*)+a-

0(2)

Test B of the suppressed decay using the SU(3) related mode:

Theory papers:Phys.Lett.B 517,125 (2001)JHEP 0106:067 (2001

PRD 67, 014011 (2003)

fa0(2)<<f

Other newideas

c0B

d

bu

d

*D

d

bc

d

0B

u

*D

0B

b

d

W W

a0(2)

b ca0(2)

b u

a0(2)

Ds(*)

B0→Ds(*)+a-

0(2)


B0->Ds(*)+a-

0(2)

•No evidence for signal•Upper limits for BF are smaller than theoretical expectation. New

Mode not usable to measure

sin (2β+γ)

232 106 B Bbar

hep-ex/0512031 (2005) Submitted to PRD

232 106 B Bbar

hep-ex/0512031 (2005) Submitted to PRD

Theory prediction:

B(B°→Dsa0) < 1.9x10-5

B(B°→ Ds a2

) < 19x10-5

B(B°→ D*s a0) < 3.6x10-5

B(B°→ D*s a2) < 20x10-5


•Vub and Vcb mediated

amplitudes both color

suppressed: •Expect large

asymmetries•But smaller branching

fractions than for D

sin(2) with B0 /B0 → D(*)0K(*)0

Critical parameter:

3 (2+2) e-i

A1VcbVus A2= rB A1e-iei

Measure the different D(*)0K(*)0 Bf Measure rB in self-tagging final state D0K*0

(assuming that rB for DK* same as rB for

DK0)

?


7712D0K*0 D0K*0

D0K0 10414 D*0K0 175 D(*)0K(*)0

232 106 B Bbar

To be submitted to PRD232 106 B Bbar

To be submitted to PRD

No signal in the suppressed mode

•rB value smaller

than theo. expectation•Not useful to measure value yet!

Equivalent Belle result on 86M BB

PRL 90, 141802 (2003)


Prospects

Most results statistically limited Effect of adding GLW and ADS to Dalitz :

Reasonable decrease in error Dalitz still dominant for measuring γ

sin(2+) from B0D(*) : 3.2 σ effect in partial reconstruction (1 ab-1) Analysis of B0D*ρ will help reduce syst.

Error on with B+

rB=0.1


Conclusions

Many new or updated results GLW: BaBar (Belle) with 232232 (275) million B’s

Clean but statistically limited. Best precision is in the D0K channel

ADS: 232 (386) million B’s rB is small: rB(D0K)<0.18

2with D: 232 (386) million B’s Challenging analysis but good agreement between experiments Interesting constraints on 2have been obtained Observation of CPV @ 3 is within reach….

Most results statistically limited: Future large luminosity data set will help Premium on coherent global analysis of world data set


B→D0K

70.2 ± 14.7 79.2 ± 15.7

149.5 ± 19.0 CP- evts

R C P + = 1:13§ 0:16§ 0:08R C P ¡ = 1:17§ 0:14§ 0:14A C P + = +0:06§ 0:14§ 0:05A C P ¡ = ¡ 0:12§ 0:14§ 0:05

PRD 73, 051106(R) (2006) 275x106 B Bbar pairs PRD 73, 051106(R) (2006) 275x106 B Bbar pairs

Belle GLW results

B→D*0K (D*0→ D00)

R C P + = 1:41§ 0:25§ 0:06R C P ¡ = 1:15§ 0:31§ 0:12A C P + = ¡ 0:20§ 0:22§ 0:04A C P ¡ = +0:13§ 0:30§ 0:08

43.9 ± 10.2

D0K+

D0K+ D0K-

D0K-

CP+ CP+

CP- CP-

32.7 ± 10.0

D*0K

CP+

D*0K

CP-

RCP+ = 1.13±0.16±0.05RCP- = 1.17±0.14±0.14ACP+ = 0.06±0.14±0.05ACP- = -0.12±0.14±0.05

RCP+ = 1.41±0.25±0.06RCP- = 1.15±0.31±0.12ACP+ = -0.20±0.22±0.04ACP- = 0.13±0.30±0.08


B0D(*) :partial reconstruction Use only the fast and soft pion tracks : no D° reconstruction !

•Combine the fast pion (2.1<p<2.4 GeV/c) with a slow pion (p<250 MeV).•Compute the mass Mmiss of the recoiling object (r.m.s. 3 MeV)

F

D0

Most of the D0 decayproduct inside this cone

P(s-)<250 MeV

E(F)~.5 mB

The unreconstructed D0 complicates vertexing and tagging

1 rad

S

B0 D*- +f

D0 -s

X


CP violation on tag side

- Potential competing CP violating effects from b → u transitions on the tag side if a Kaon is used to tag the B

SK 2 r (sin(2 )

+ 2 r’(sin(2 ’)

Rewrite as S = (a c) + b a = 2r sin(2) cos ()

c= cos(2) [2r sin()+2r’sin(’)]

b = 2r’ sin(2) cos (’)

Slept 2 r (sin(2 )lepton Tags

Kaon Tags

BaBar: fit CP observables a and clepton (free of tag-side CPV).Belle: Fit S+ and S- (partial reco: only lepton tags) Full reco: use all tags but measure tag side CPV parameters S+’ and S-’ from a sample of D*l evts [only tag side cpv) a = (S++S-)/2 c = (S+-S-)/2

free of tag-side CPV

Lepton tags free of tag-side CPV


PRD 72 (2005) 032004

B-→D(*)0K(*)- ADSSuppressed channel not visible in D(*)0KSuppressed channel not visible in D(*)0K

B→ D0KB→ D*0K(D*0 → D00)

B→ D*0K(D*0→D0)

R K ¼< 0:029 R ¤K ¼;D 0¼0 < 0:023 R ¤

K ¼;D 0° < 0:045

r*B2<(0.16)2 @ 90% C.L.

Bondar & Gershon PRD70,091503(2004)

R ¤K ¼;D 0¼0 +R ¤

K ¼;D 0°

2¡ r2

D = r¤B

2B→ D0K*

RSK ¼ = 0:046§ 0:031§ 0:008

4.2 2.8 ev

PRD 72 (2005) 071104

Constraints on rB from D*0K

RADS < 0.029 RADS < 0.023 RADS < 0.045

RADS=0.046±0.031±0.008

232 106 BBS


BaBar constraints on rB

D0 K

48o<<73o

For maximum mixing (/φ3=0, δ=180°):

rB<0.23 @ 90% C.L.

R K ¼ = r2B + r2

D + 2rB rD cos(°)cos(±)

1-C

L GLWADScombination1

2

3

rSB

[0,] & (D+B)[0,2]D0K*+

rSB=

DK*, GLW+ADS combined

RKπ<0.029

RKπ= r2B +r2

D + 2rB rD cos(γ) cos(δB+ δD)


sin(2φ1+φ3) (Belle)

(*)00 )( DBB *00 )( DBB

- full reconstruction 0* DD

D*π full rec

D*π partial rec(only lepton tags)

357 fb-1 ~ 392 106 B Bbar357 fb-1 ~ 392 106 B Bbar

PRD 73 092003 (2006)

Documents

Beauty 06, Oxford, 27 Sept. 2006 Marco Zito1 Measurements of gamma using ADS, GLW and other methods & future projections Marco Zito CEA-Saclay, Dapnia-SPP