Download - Measurements of g and sin(2 b+g ) in BaBar
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Gianluca Cavoto1
Measurements of and sin(2) in BaBar
Gianluca CavotoPrinceton University
Università di Roma ‘La Sapienza’On behalf of the
BaBar Collaboration
ICHEP'04 32nd International Conference on
High Energy Physics
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Gianluca Cavoto2
Angle of the Unitarity TriangleMeasure 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
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Gianluca Cavoto3
from direct CP violation
Relative size (rB) of B decay amplitudes
Different incarnations…
Not well constrained by theory.Larger rB, larger interference, better experimental precision
Relative strong phase (B) unknown
( )( )B
A b urA b c
Interference 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
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Gianluca Cavoto4
Gronau London Wyler method
CP modes: small D0 branching ratio
D decays into CP eigenstate
Select CP-even and CP-odd final states
Theoreticallyclean, but with 8-foldambiguity
0 02
0
( ) ( ) 1 2 cos cos2 ( )CP CP
CP B B BB D K B D KR r r
B D K
0 0
0 0
( ) ( ) 2 sin sin( ) ( )
CP CPCP B B CP
CP CP
B D K B D KA r RB D K B D K
3 observables, 3 unknowns
2)(000 DDDCP
Normalize to D0 decay into flavour state (K-+)Experimentally
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Gianluca Cavoto5
Analysis techniques
Cerenkov angle No charge confusion. Clear separation D/D
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
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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 5.8CP 34.4 6.9CP
Adding KS, KS
D0CP K - CP+ (+-,K+K-) CP- (KS0)
D0CP K* - (K* - KS-)
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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* - (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 final states still to be added…
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
RA
D*0 (D0CP0)K -
NBB=214 106 NBB=227 106
NBB=123 106
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Gianluca Cavoto8
Atwood Dunietz Soni method
0
0
| ( ) | 0.060 0.003| ( ) |DA D KA D
rK
Input:
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 rBr K K Br K K
([ ] ) ([ ] ) 2 sin( )sin /([ ] ) ([ ] )ADS B D D B ADS
Br K K Br K KA r r RBr K K Br K K
D decay into flavor state
Phys.Rev.Lett.91:171801,2003
B D
D decay strong phase D unknown
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Gianluca Cavoto9
ADS results
D0K D*0(D00)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
K
NBB=227 106
No signal in current dataset
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Gianluca Cavoto10
rB from 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
anyr
any
D0K D*0(D00)K D*0(D0)K
Sensitive to rB (RADS~r2B)
Not easy to determine
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Gianluca Cavoto11
B- D(*)0 - D0(S) Dalitz analysis
=75,=180,rB=0.125
Isobar model for f(m2+ ,m2
- )can fix phase variationD across Dalitz plot.
Only two-fold ambiguity in extraction
Sensitivity to
Amplitude for B-/B+ “D0”K-/K+
202 )( SKMm
202 )( SKMm
If we knew the charm phase shift D?
DCS K*(892)
(770)
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Gianluca Cavoto12
D0(S) Dalitz model
Plot of mpipi
Determined on D* D0 sample
No D-mixing, No CP violation in D decays
(770)
CA K*(892)
DCS K*(892)
2m
2m2m
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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(D00)K
D*0(D0)K
2m
2m2m
2m
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Gianluca Cavoto14
from B-D(*)0[S]
With current statistics, no rB sensitivity for rB<0.10
0.18 (90% )Br CL * 0.24 (90% )Br CL
Bayesian confidence 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
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Gianluca Cavoto15
Critical rB…
rB
D0 Dalitz
(
) 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
211
ADS B
D
B
A SB
R rA Ar
R r
GLW ADS
= 62o
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Gianluca Cavoto16
sin(2+) with B0 D(*)-+/+ Time dependent CP analysis
favored bc amplitude suppressed bu 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 BB Continuum
Lepton tag
*0 DBsoftD
0
X
Asymmetry parameters
2 sin(2 )cos
2 cos(2 )sinlep
a r
c r
~ ~
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Gianluca Cavoto17
B0 D(*)0(*)0
(*)0 00
00 (*)0
( )
( )
B D KrB 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
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Gianluca Cavoto18
Unitarity triangle constraintsConfidence regions in plane
Combination of BaBar a and c results with uniform prior in r
Search for B0 DsImprove bound using SU(3) r from B0D+
s-
3( ) 9.5 10 90% . .r D at C L
Not encouraging for D…
http://www.utfit.org
NBB=90 106
.
68% C.L. 95% C.L.
(*)
(*)
0 (*)(*)
0 (*)
( )tan( )
S
S DC
D
fBR B DrBR B D f
Phys.Rev.Lett.90:181803,2003
* 0.0050.007
0.019 0.004
0.017
r
r
hep-ph/0408079
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Gianluca Cavoto19
– More modes and techniques added to measure GLW, ADS, D0K Dalitz, time-dep. sin(2+)
– No single golden technique– Constraints on b u amplitude in B DK
Evidence 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 urA b c
95 % C.L.
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Gianluca Cavoto20
Backup slides
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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 Dflavor