cp violation at b-factoris introduction 1 / 2 / 3 / vub, d mixing, bs conclusion pavel...
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CP violation at B-factoris
• Introduction• 1/• 2/• 3/• Vub, D mixing, Bs• Conclusion
Pavel KrokovnyKEK, Tsukuba, Japan
KEK
Unitarity triangle
1)1(
2/1
)(2/1
23
22
32
AiA
A
iA
VVV
VVV
VVV
V
tbtstd
cbcscd
ubusud
* *ub ud tb td* *cb cd c
* * *ub ud cb cd tb td
b cd
V V V V
V V V V
V V V V V Vi k :=1, = + + =0
+ 1
3
+ = 0
Using unitarity requirement:
We need to measure all the angles to test SM.
CPV in Mixing
B0 fCP
B 0
Af
Af
2ie
2
B0
fCPB 0Af
Af
2ie
2
02
0
( )
( )CP
i CPf
CP
A B fe
A B f
0 02
0 0
2
2
2Im ( ) ( ) 1 | |( )
( ) ( )1 | |
[ sin cos ] 1 | |
CP
CPCP
CP
C
CP C
CP
P
PCP
f
CP CPff
CP CP
fCP
f
f
f
f f
B f B fA t
B f B f
m t m t C
S
CS
Difference in decayrate for B0 and B0
CP Violation
Direct CPV in charged B Decays
wk sti iδ2A e e
B f
wk stΓ(B f) Γ(B f) for 0 and δ 0
2
1 2( ) wk sti iB f A A e e st
B fwk
wk
B f2
1 2( ) wk sti iB f A A e e
One rate asymmetry is not sufficient to extract physical parameters:
• measure A and A, but need A1, A2, wk, st
CP violation through interference of decay amplitudes
1A
1A
2A
2A
1 22 2
1 2 1 2
2 sin( )sin( )( ) ( )
( ) ( ) 2 cos( )cos( )wk
CPt
w
s
stk
A Af fA
f f A A A A
dj
j d
G - G= =
G +G + +
KEKB and Belle
KEKB Collider
3.5 GeV e+ & 8 GeV e– beams
3 km circ, 11 mrad crossing angle
L= 1.65 x 1034 cm–2s–1
world record
L dt = 740 fb–1 @ Υ(4S)+off(~10%)
Event shape*2 *2
ES beam Bm E p * *B beamE E E
(mES) 3 MeV (E) : mode dependent
qq events(q=u,d,s,c)
BB events
(4S) rest frame
Event shape variables examples:
Kinematics and event shape
1 from the “golden” bccs mode-
Measuring cos2
B → D(*)0 h0 with D0 → KS(same weak phase
as B0 → J/K0)
cos2 consistently measured to be > 0!
sin21=0.75 ±0.44±0.22 cos21=1.79 ± 0.53 ± 0.33cos21>0 @ 98.3% CL
cos>0 solutions excluded:
β = (21.3±1.0)°
CPV in B0 → D+D-
sin2 from Penguin Decays
• no weak phase in b→(qq)s penguin decays– expect to measure S = sin(2) [just as in B → ψ KS]– contributions from suppressed diagrams expected to be
small (sin(2) = sin(2eff) sin(2) ~ 0.01-0.1)• if new physics introduces weak phase in decay, we could
measure something different than sin(2)
newphysicsb
sssd
dg
t
SK
0B,
W
Standard Model New Physics
b
d0B
sssd SK
,
NP weak phase no weak phase from decay
sin2 in bsqq Penguins
No significant deviations from the WA from the value from the bccs modes: sin2 = 0.68±0.03
sin2
sin2eff 1
eff
HFAG advises extreme caution when interpreting this average (assumption of Gaussian errors not justified for all measurements)
Determination of 2()Time-dependent CP asymmetry: )cos( )sin( )( tmCtmStA dd
Tree:
00-0 A A2/1 A
Penguin:
)sin(2 )sin(21 0 eff2 CSC
Without penguin: Including penguin:
Use isospin relations to estimate the penguincontribution:
-00 A A Neglecting EWP, h+ h0 (I=2)=pure tree
Gronau-London, PRL, 65, 3381 (1990)Lipkin et al., PRD 44, 1454 (1991)
0 C )2sin( S
2() Measurement using B
.)(04.0.)(10.061.0
.)(05.0.)(08.055.0
syststatS
syststatA
t (ps)
PRL 78, 211801 (2007)
Sorting out penguin pollution
Triangle analysis6 observables6 unknowns
WA values
°±°
B isospin analysis
WA values
°< 2<°
2
21
22
21
2
21
2
coscossinsin14
1
4
9
coscos
1 LL ff
dd
d
B0+– has 3 polarization states with different CP eigenvalues
Fortunately, longitudinal polarization dominates pure CP-even stateNo significant 00 signal small penguin contribution
B CP fit results
PRD 76, 011104 (2007)
B →
0 3.6 63.9
0 6
0 0 0 6
+ +0.026L 0.013
(25.5 2.1 ) 10 [arXiv: 0705.2157v2]
(16.0 2.2 2.3) 10 [PRL 97, 261801 (2006)]
(1.07 0.33 0.19) 10 [PRL 98,111801 (2007)]
f 0.992 ± 0.024 [arXi
Br B
Br B
Br B
+0 +0.023L 0.02700L
0
0.05-0.06
v:0705.2157] f 0.905 ± 0.042 [PRL 97, 261801 (2006)]f 0.87 ± 0.13 0.05 [PRL 98,111801 (2007)]
0.12 0.13 0.10 [PRL 97, 261801 (2006)]
0.17 0.20 [arXiv:0705.
CPA
S
2157]0.01 0.11 0.06 [arXiv:0705.2157]C
Small penguins !
Dominantly longitudinally polarized !
Large branching fraction !
arXiv: 0705.2157v2
B0 tag
B0 tag
BABAR
Time-dependent CP asymmetries in B0 →
0B BaBar: 383 MBB
729 60 signal events
with B →
| |16.5 (90% C.L.)
effo
With more data information onS00 and C00 will allow to resolve
discrete ambiguities
00
000.5 0.9 0.2 0.4 0.9 0.2
SC
0 0 085 28 17 (3.6 σ significant, incl. syst.)
B
0 0 0 6
00L
(0.84 0.29 0.17) 10f 0.70 ± 0.14 0.05
Br B
arXiv:0708.1630
B0()0 Dalitz Analysis
B0
B0–
Various (24) Patterns of Interferences Information on Relative Phases
Interference by B0B0 oscillation + Interference Between , ,
Dalitzt
Pentagon analysis
°< 2<°
PRL 98, 221602 (2007)
2 results:
B
BB
~90o±10o
Determination of
Relative phase: (B– DK–), (B+ DK+)
includes weak (γ/φ3) and strong (δ) phase.
3*1 ~~ AVV uscbA i
csub ei(ρ~AλV~V ~)3*2A
If D0 and D0 decay into the same final state, 000~ DreDD i
B– D0K–: B– D0K– :
Amplitude ratio:
Possible D0 / D 0 final states:CP eigenstates, KK)Flavor eigenstates (K)Three-body decays (KS)
Gronau & London, PLB 253, 483 (1991) Gronau & Wyler, PLB 265, 172 (1991)Atwood, Dunietz, & Soni, PRL 78, 3257 (1997),Atwood, Dunietz, & Soni, PRD 63, 036005 (2001)Giri, Grossman, Soffer, & Zupan, PRD 68, 054018 (2003)Bondar, PRD 70, 072003 (2004)
0 0| ( ) | / | ( ) |~ 0.1r A B D K A B D K
Parameters are obtained from the fit to Dalitz distributions of D Ksπ+π– from B±DK± decays
Dalitz analysis method
Using 3-body final state, identical for D0 and D0: Ksπ+π-.Dalitz distribution density:
22222 ||),(
ssss KKKK
dmdmmmd A
222 |),(| ss KKmmA
(assuming СР-conservation in D0 decays)
000~ DreDD i
),( 22 ss KK
mmf is determined from D*– D0π–, D0 Ksπ+π– decay model uncertainty of the result
),,( 3r
A.Giri, Yu. Grossman, A. Soffer, J. Zupan, PRD 68, 054018 (2003)A.Bondar, Proceedings of the Belle Workshop, September (2002)
Dalitz analysis: sensitivity to the phase
Belle/Babar results on γFit parameters are x= r cos(φ3+δ) and y= r sin(φ3+δ)
(better behaved statistically than r, φ3 and δ)Belle/Babar measurements in good agreement
Note: σγ depends significantly on the value of rB
Contours do not include Dalitz model errors
Contours do not include Dalitz model errors
rB
2γ
Dalitz analysis (Belle)
BDK
BD*K
BDK*
Combined for 3 modes: φ3=53°+15 3° (syst)9° (model)
8°<φ3<111° (2σ interval)
rDK =0.159+0.054 0.012(syst)0.049(model)
CPV significance: 78% rD*K=0.175+0.108 0.013(syst)0.049(model)
rDK*=0.564+0.216 0.041(syst)0.084(model)
-0.099
-0.050
-0.155
-18
φ3=66 -20 °(stat) φ3=86 -93°(stat) φ3=11 -57°(stat)+37 +23+19
from BD(*)0K, D0KS (Babar)
B- DK- B+ DK+
Dalitz distribution of selected B± candidates
2
1
Stat Syst Model
rB 0.142 rB 0.198 0.016 rB
* 0.206 rB* 0.282
=(92±41±11±12)°
Constraints of the Unitarity Triangle
Estimated average with GLW, ADS, Dalitz and sin(2φ1+φ3)
~80o±30o
Model-independent approachA.Bondar, A.Poluektov hep-ph/0510246
50 ab-1 at SuperB factoryshould be enough for model-independent γ/φ3 Measurement with accuracy below 2°
~10 fb-1 at ψ(3770) needed to accompany this measurement.
A.Giri, Yu. Grossman, A. Soffer, J. Zupan, PRD 68, 054018 (2003)
rB=0.2
Summary in pictures
CPV angles
CP-conserving quantities
Summary in pictures
Summary
φ1 is measured with 1º accuracy. Still there is room for improvement.
Remarkable progress in φ2 measurement: accuracy of O(10º) is achieved using and Still limited by statistic - improvements in the future.
The φ3 remains the most difficult angle of the Unitarity
Triangle to measure. Good perspectives with higher statistics since the theoretical uncertainties are very low. Model error can be eliminated using charm data: CLEOc/BES.
No indication for a New Physics is found so far...Much more data is necessary LHCb, Super B factory.
PEP-II and BaBar
e-
e+
1.5T magnet
ElectromagneticCalorimeter (EMC)
Detector of Internally Reflected Cherenkov Light (DIRC)
Drift Chamber (DCH)
Silicon Vertex Tracker (SVT)
Instrumented Flux Return (IFR)
3.1 GeV e+ & 9 GeV e– beams
L= 1.12 x 1034 cm–2s–1 (June 28, 2006)
L dt = 380 fb–1 @ Υ(4S)+off (~10%)
Future plans of KEKB• Next milestone
– Accumulation of 1000 fb-1 (740 fb-1 at present)
• Near term plans– L = 2 x 1034cm-2s-1
• Benefits of crab crossing• Higher beam current (HER) 1400 -> 1500mA with several reinforcements of vacuum components• Search for better machine parameters
– Beam emittance, x*, x etc.• Long-term future plan
– SuperKEKB• Major upgrade plan of KEKB• Design luminosity: ~ 1036cm-2s-1 • Not yet approved (Construction hope to start in FY 2009)
Bρρ
2
21
22
21
2
21
2
coscossinsin14
1
4
9
coscos
1 LL ff
dd
d
B0+– has 3 polarization states with different CP eigenvalues
021.0029.0014.0978.0
Lf
030.0 9410 03400400
..L .f
BelleFortunately, longitudinal polarization dominates, therefore, pure CP-even state
BaBar (PRL 95, 041805, (2005)):
Belle (hep-ex/0601024): cos
# of
Eve
nts
No significant 00 signal small penguin contribution
BaBar (PRL, 98, 111801 (2007)):
000=(1.07 ±0.33 ±0.19) 10-6)( BB
ADS methodD. Atwood, I. Dunietz and A. Soni, PRL 78, 3357 (1997); PRD 63, 036005 (2001)
Enhancement of СР-violation due to use of Cabibbo-suppressed D decays
B–D0K– - color allowed D0K+π– - doubly Cabibbo-suppressedB–D0K– - color suppressed D0K+π– - Cabibbo-allowed
Interfering amplitudesare comparable
coscos2)(
)(3
22DBDBDK rrrr
KDBBr
KDBBr
fav
suppR
ADS method
Belle results (357 fb-1)
Suppressed channel not visible yet:
34.89.7 10)0.10.0(
DKR
Using rD=0.060±0.003, for maximum mixing (φ3=0, δ=180°):rB<0.18 (90% CL)
3119 1013 DKR
3106][*
1020
KDD
R
31813][* 1011 KDD R
rB<0.23 (90% CL) for BDKrB<0.16 for BD*K
BaBar results (211 fb-1)
GLW method
M. Gronau and D. London, PLB 253, 483 (1991); M. Gronau and D. Wyler, PLB 265, 172 (1991)СР eigenstate of D-meson is used (DCP).
CP-even : D1 K+K–, π+ π –
CP-odd : D2 KS π0, KS ω, KS φ, KSη…
)()(
)()(
2,12,1
2,12,121
KDBBrKDBBr
KDBBrKDBBr,Α
32
3
coscos21
sinsin2
rr
r
for D1
for D2
32
002,12,1
2,1 coscos21)(/)(
)(/)(
rrDBBrKDBBr
DBBrKDBBrR
4 equations (3 independent: ), 3 unknowns ),,( 3r
Additional constraint:
СР-asymmetry:
A1,2 of different signs
2211 RARA
GLW averages
DC
P K
*D
* CP K
DC
P K
GLW method
0 0
0 0
2
0 0
0 0
2
( ) ( )
[ ( ) ( )]/ 2
1 2 cos
( ) ( )
( ) ( )
2 sin
1 2
cos
sin
coscos
CP CPCP
CP CPCP
CP CP
BR B D K BR B D KR
BR B D K BR B D K
r r
BR B D K BR B D KA
BR B D K BR B D K
r
r r
0.81 0.10 0.05
1.07 0.10 0.04
0.19 0.12 0.02
0.35 0.09 0.05
CP
CP
CP
CP
R
R
A
A
First evidence (3.4) for direct CP violation in B → DK decays
0CPB D K 0
CPB D K
85 14 signal events177 20
signal events
Dalitz analysis (Belle)
Belle result (357 fb-1) PRD73,112009
331±17 events 81±8 events 54±8 events
BDK
BD*KBDK*
B- B+ B- B+ B- B+
Dalitz analysis: D0 Ksπ+π– decay
Statistical sensitivity of the method depends on the propertiesof the 3-body decay involved
(For |M|2=Const there is no sensitivity to the phase θ)Large variations of D0 decay strong phase are essential
Use the model-dependent fit to experimental data from flavor-tagged D* D0π sample ( >2x105 events)
Model is described by the set of two-body amplitudes + flat nonresonant term
As a result, model uncertainty in the
γ/φ3 measurement
ρ-ω interference
Doubly Cabibbosuppressed K*
)(GeV22sK
M
)(GeV22sK
M
)(GeV22sK
M )(GeV22sK
M
)(GeV 22
M )(GeV 22
M
M
(
GeV
2 )
Ksπ
–
2
D0 Ksπ+π– decay model
Dalitz analysis (Belle)Fit parameters are x= r cos(φ3+δ) and y= r sin(φ3+δ)(better behaved statistically than ) are obtained from frequentist statistical treatment based on PDFs from toy MC simulation.
3,, r3,, r
BDK
BD*K BDK*
easier to combine results
x–= 0.025 -0.080
y–= 0.170 -0.117
x+= –0.135 -0.070
y+= –0.085 -0.086
x-= –0.128 -0.146
y-= –0.339 -0.158
x+= 0.032 -0.116
y+= 0.008 -0.136
x–= –0.784 -0.295
y–= –0.281 -0.335
x+= –0.105 -0.167
y+= –0.004 -0.156
+0.072
+0.093
+0.069
+0.090
+0.167
+0.172
+0.120
+0.137
+0.249
+0.440
+0.177
+0.164
sin(2φ1+φ3) from B0 D*π decay
)sin()cos(18
1)( /||(*)0 tmStmCeDBP Bt
B
)sin()cos(18
1)( /||(*)0 tmStmCeDBP Bt
B
),2sin()1(1
2312
L
R
RS
11
12
2
R
RC
where
Use B flavor tag, measure time-dependent decay rates:
Decay : (*)00 )( DBB
+
B D-+
Btag B0
Btag B0
CP violation
02.0R
sin(2φ1+φ3) result (211 fb-1) hep-ex/0601018result (357 fb-1) hep-ex/0604013
*
0
DB
BB
rec
tag
*
0
DB
BB
rec
tag
*
0
DB
BB
rec
tag
*
0
DB
BB
rec
tag
*
0
DB
BB
rec
tag
*
0
DB
BB
rec
tag
*
0
DB
BB
rec
tag
*
0
DB
BB
rec
tag
Lepton tags, D* final state
New
New
sin(2φ1+φ3)
90% CL
68% CL
|sin(2+)| > 0.64 @ 68 % C.L.|sin(2+)| > 0.42 @ 90 % C.L.
Combine partial and fully reco results and use the R parameters from SU(3) symmetry
Frequentistconfidence level
|2+| = 90o 43o
30% theoretical error on rf
DBB )( 00 *00 )( DBB
|sin(2φ1+φ3)|> 0.44 |sin(2φ1+φ3)|> 0.52
R~0.02 from
New
New
Br(BDS(*)π)/Br(BD(*)π)
D0-D0 mixing
D0-D0 mixing
D0-D0 mixing