Measurements of g and sin(2 b+g ) in BaBar
description
Transcript of Measurements of g and sin(2 b+g ) in BaBar
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
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
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
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
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
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-)
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
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
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
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
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)
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
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
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
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
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
~ ~
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
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
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.
Gianluca Cavoto20
Backup slides
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