CP VIOLATION at B-factories
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Transcript of CP VIOLATION at B-factories
CP VIOLATION at B-factoriesA.Bondar (Budker INP,Novosibirsk)
Measurements of large CPV in bc c s modes
Search for New Physics: CPV in bs penguin modes
Measurement of CPV in B+–
See also Today A.Mihalyi “Recent results on the CKM angle α from BABAR”
New method of the measurement in BD0K based on Dalitz plot analysis of the three body D0KS+–decay
See also Today M. Legendre “Status and prospects for the measurement of angle γ ”
T. Gershon “Measurement of φ3 using B– to DK– with D to Ks π+π–”
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Coupling strength at decay vertex : gFVij
universal Fermi weak coupling : gF
Vij : quark-mixing matrix elements
CKM matrix : unitarity : Vji*Vjk=ik explicit parametrization (Wolfenstein) complex phase leads to different bu and td amplit
udes for quarks and anti-quarks.
V Vud Vus Vub
Vcd Vcs Vcb
Vtd Vts Vtb
1 2 2 3A i 1 2 2 2A
3A 1 i 2A 1
(4 )
CP0.2235±0.0033 A 0.81±0.08 |i| 0.36±0.09 |i| 0.79±0.19
The Weak Decays of Quarks
quark decay
gFVijij
W
quark decay
gFVij*i
j
W
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The Unitarity Triangle
Using orthogonality relation
* *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
B0 B0
B0 D(*)B+ DK
B0 J/Ks
B0 Ks
B0 D(*)D(*)
*ub ud*cb cd
V V
V V
*tb td*cb cd
V V
V V
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CKM CP phenomenology
CP violation arises from the interference of two amplitudes with different phases.
Mixing induced CP violation : Indirect CPV Decay amplitudes asymmetry: Direct CPV
Single CKM phase = unique source of CPV ? It is difficult for CKM CPV to explain the observed
matter/antimatter asymmetry in the universe. It is needed to search for Beyond SM !
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)}]sin(
)cos({1[);(/||
tmS
tmAe
tfBPBt
CP
Time-dependent CP violation
If either S or is non-zero, B fCP has CP asymmetry.If either S or is non-zero, B fCP has CP asymmetry.
0
0
0
0
CP CPf
B
BB f
B
CPfA
CPfA
CPfA
CPfAmixing mixing
decay decay
0 0q = 1 = ( ) for tag-side B B
Mixing induced CPV param.
Direct CP violation param.
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KEKB & BELLEBELLE detector
KEKB Collider
~350 scientists, 55 institutions3.5GeV e+ & 8GeV e Asymmetric Collider3km circumference, 11mrad crossing angleL= 1.3 x 1034 cm–2s–1 (world record)Ldt = 266 fb–1 @{Y(4S)+off(~10%)}
(140fb1 : 1.52 x 108 )
BB pairs
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PEPII & BABAR
BABAR Detector
PEPII Collider
3GeV e+ & 9GeV e Asymmetric Collider
L= 0.92 x 1034 cm–2s–1 Ldt = 214 fb–1 @{Y(4S)+off(~10%)}
Cherenkov Detector (DIRC)
Silicon Vertex Tracker
Instrumented Flux Return
CsI(Tl) Calorimeter
Superconducting Coil (1.5T)
Drift Chamber
e- (9 GeV)
e+ (3 GeV)
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e e+e: 8.0 GeVe+: 3.5 GeV
BCP
z
Btag
(4S) ~ 0.425
fCPfCP
z cB ~ 200 m
Flavor tagFlavor tag
4 steps toward the CP violation measurement
• Reconstruct B fCP decays
• Determine the flavor of Btag • Measure proper-time interval : t • Evaluate asymmetry from the obtained t
distributions
How to measure CP violation ?
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tags)(poor
tags) (good
DCPV No 0.0411.007 ||
0.0280.0570.733sin2
scc
1
06.073.02sin 1
13.080.02sin 1
hep-ex/0308036
0.0490.736)2WA2003(sin
tmeasuremen precision a becoming Now
1
sin21 : bbccsccs BB140 fb ~152M pairs- 1
BaBar 81 fb-1: sin(2φ1) =0.741±0.067±0.033
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cos21 from B
J/J/
Moriond04,
M.Verderi
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cos21 from B
J/J/
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cos21 from B
J/J/
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Non-Standard-Model particles could appear in the
penguin loop, modifying rate and/or CP asymmetry
Non-Standard-Model particles could appear in the
penguin loop, modifying rate and/or CP asymmetry
In the SM, for pure bs penguin transition modes sin21eff = sin21(BJ/KS)
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L = 108 fb-1L = 108 fb-1hep-ex/0406005
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L = 111 fb-
1
L = 111 fb-
1
BELLE PRD 60, 012001(2004)
hep-ex/0406005
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sin21 Summary
Points of B0 π+π–
decay sensitive to CKM angle 2
direct CP violation may also occur because of interference between
b u tree amplitude and
b d penguin amplitude
It’s very important to check the KM matrix by other measurements.
b ud
B0 dW+
d
B0b
dB0
duud
gt
0 = = (1)Amp( ) = T + P tb td*
ub ud
*V VbO
a V VB a b
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)(
)(
0
0
3
3
2
3
3
|/|1
|/|1
),||)|(|)(
),||)|(|)(
i
ii
iii
iii
eTP
eTPe
ePeeTBA
ePeeTBAPT
PT
221
21
12
212
|/|cos)cos(|/|21
,/]sin)sin(|/|2[
,/]2sin|/|
cos)sin(|/|22[sin
TPTPR
RTPA
RTP
TPS
TP
Constraints on the CKM angle 2
4 parameters
|P/T| 0.15-0.45 (representative) Theory ~0.31 23.7 deg (Belle & BaBar combined)
Strong phasedifference
convention taken fromM.Gronau and J.L.RosnerPhys. Rev. D65, 093012 (2002)
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sin22 : bbuuduud , B0
High Quality Events
Low Quality Events
L = 140 fb-1L = 140 fb-1
S
A
Significance
Feldman-Cousins Analysis
(5.2 Observation of CP violation
3.2 for A=0 and any S
Evidence for direct CP violation
3.3 for “superweak” case
hep-ex/0401029
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History of A and S
Belle
BaBarThis resultBelle 140fb1
Difference still at ~2.0 levelDANE04 Frascati June 7, 2004
Constraint on 2 and |P/T|
Belle140fb1
12
3
|P/T| > 0.17[95.5% C.L. (2)]
2 (
deg.
) (deg.)
2 (
deg.
)321
90 ≤ 2 ≤ 146 (95.5% CL) |P/T| =0.3
|P/T|
|P|/(|T|+|P|)
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sin22 : bbuuduud , B0
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measurement, BDD(*)0(*)0KK
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measurement, BDD(*)0(*)0KK
ρ-ω interference
Doubly Cabibbosuppressed K*
Construct f as sum of known two-body resonances plus non-resonant term, fit to continuum D*-to-D-to-Kππ data.
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measurement, BDD(*)0(*)0KK
L = 140 fb-1L = 140 fb-1
73 events 73 events
B+ D(*)0K+ fit result
r+=0.40±0.15, θ+=256±19°
r- =0.21±0.15, θ- = 71±37°
B+ D0K+ B+ D*0K+
r+=0.29±0.19, θ+=353±38°
r- =0.38±0.19, θ- =249±32°
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measurement, BDD(*)0(*)0KK
Combined fit:
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Conclusion
Belle and BaBar continue to refine their measurements of from ccs
modes.
Belle and BaBar continue to refine their measurements of from ccs
modes.
__
Both experiments are using their high-luminosity data samples to probe for new physics in rare B decays: over-constrain the sides
and angles of the Unitarity Triangle.
Both experiments are using their high-luminosity data samples to probe for new physics in rare B decays: over-constrain the sides
and angles of the Unitarity Triangle.
todaytoday this summerthis summer in two years?in two years??
140fb-1140fb-1 270fb-1270fb-1 >500fb-1>500fb-1
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Conclusion
Many new/updated results utilizing ~230–280 fb-1 of data per experiment will be shown
this summer.
Watch this space!
CP eigenstates
category CP mode process CP(f) SM prediction
S A Penguin
charmonium
J/ KS f sin21 0 negligibl
e(2S) KS
C1 KS
C KS
J/ K*(KS0)
J/ KL
charmonium
J/ 0 f sin21eff yes
double charm
D(*)D(*) small yes
bs penguin
KS f sin21 small dominan
t’ KS
K+KKS
hh f sin22eff yes
b ccs
b ccd
b uud
b sqq
(f CP eigenvalue)
0
0
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Continuous Injection
sin22 : bbuuduud
Time-dependent CP asymmetries in B0 π+π– -- the best way to access the CKM angle 2
0
0
| |/
( ) [1 { sin( )
cos( )}]
Bt
qd
d
eP t q S m t
A m t
2
2 2
2
1 2, ,
1 1
( )
( )M
i
ImA S
A B fe
A B f
= +1 for B0 tag 1 for B0 tag
direct CP asymmetry
t=z/(c)
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sin22 : bbuuduud , B0
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sin22 : bbuuduud , B0
L = 113 fb-1L = 113 fb-1