beauty 06, oxford, 27 sept. 2006 marco zito1 measurements of gamma using ads, glw and other methods...
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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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 2
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)
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 3
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 4
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 5
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!
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 6
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)
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 7
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+
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 8
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 9
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 10
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 11
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)
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 12
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 13
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 14
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 15
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)
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 16
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 17
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!
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 18
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 19
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 20
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)
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 21
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 22
•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)
?
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 23
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)
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 24
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 25
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 26
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 27
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 28
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 29
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
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 30
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)
Beauty 06, Oxford, 27 Sept. 2006 Marco Zito 31
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)