Transcript スライド 1 - University of California, San Diego

“sin2f1” measurement with bs
penguin decays at Belle
Koji Hara (Nagoya University)
for the Belle Collaboration
• Introduction
• Measurement of time-dependent CP
violation (tCPV) in B0h’K0
• tCPV result for B0KSp0
Page 2
2015/7/7
Introduction
tCPV measurements in B0 decays
b→ccs tree
_
_
B0
b
d
w
c
c
_
s
d
S=sin2f1 , A ~ 0
SM Anchor
b→sqq penguin
J/
K0
B0
_
w
b
t
d
_
g
s η’,φ…
s
_
s
0
K
d
Check if
“sin2f1” ≡-ξfS= /sin2f1, A ~ 0
Extra CPV phase
“sin2φ1“≠sin2φ1
Hint of New Physics
SM Contamination
• It is essential to estimate possible deviation
from sin2f1within the SM to claim new
physics.
P
– bu Tree contamination
W
b
2s
t
s
s
d
g
d
mode
CP
fKs
KsKsKs
K+K Ks
hKs
1
+1
f0Ks
Ks
pKs
P
P’
T
T’
~+1
































P’
T
T’
W
b
2s
t
d
d
d
g
d
b
d
W
4
W
b
d
4
u
u
s
d
u
s
u
s
s
d
– Final state rescattering
Page 4
2015/7/7
Theoretical Estimation
h’K0, fK0, KSKSKS are the “Golden modes” with the
smallest expected difference from sin2f1 in SM
• Expected differences are mostly positive.
•
For example,
[Chua, talk at FPCP06, hep-ph/0605301]
Page 5
2015/7/7
Page 6
2015/7/7
New tCPV result for B0h’KS+h’KL
Page 7
2015/7/7
Event Selection
• Dominant Background is e+e-  qq continuum
 Distinguished from signal by the Likelihood
Ratio made with event shape variables.
Event Shape
Bkg
e e
4S
BB
(Spherical)
e e
signal
qq
(Jet-like)
Likelihood Ratio
Page 8
2015/7/7
0
B h’K
S
Signal
• Event-by-event signal fractions extracted from 3D Mbc-DE-LR fit.
LR<0.5
LR
h’ rg
LR0.5
Ks(pp)
794  36
 h(2g)pp Ks(pp)
363  21
 h(3p)pp Ks(pp)
100  11
Ks(pp)
103  15
rg
h(2g)pp Ks(pp)
Page 9
Total
62  9
2015/7/7
1421  46
0
B h’K
L
Signal
• Signals are extracted from PB*-LR 2D fit
Background
subtracted
h’h(2g)pp KL 392  37
h(3p)pp KL
Total
LR
Page 10
62  13
454  39
PB*(GeV/c)
2015/7/7
0
0
B h’K
Result
Background subtracted
“sin2f1”=  0.64  0.10  0.04
A =  0.01  0.07  0.05
• Consistent with sin2f1
• 5.6s First observation of
tCPV in bsqq penguin
good tag
Page 11
2015/7/7
CP Fit Results for B0h’KS, KL
h’KS Background subtracted
“sin2f1”
good tag
h’KL Background subtracted
good tag
Page 12
A
errors are statistical only
2015/7/7
New tCPV result for B0KSp0
Page 13
2015/7/7
tCPV in KS
0
p
• bs penguin dominant mode
S  sin2f1 (Possible deviation within SM ~O(0.1) )
• A Member of Kp Family
A is important to check the sum rule
A(K+p-)+A(K0p+)=A(K+p0)+A(K0p0)
[Gronau, Phys. Lett. B627, 82 (2005)]
• No primary tracks from B vertex
– Vertex reconstruction with KS trajectory
Page 14
2015/7/7
0
B K
S
0
p
Signal
LR<0.7
LR0.7
Signal yield: 515  32
Page 15
2015/7/7
Vertex Reconstruction with KS
p p • Extrapolate KS track to the
Interaction Point
Ks track
– Vertex reconstruction efficiency ~33%
IP profile
Raw asymmetry
BCP vertex
• Events without the vertex can still
be used for A measurement.
J/yKS with the KS Vertexing
• The validity is confirmed with
the J/yKS as control sample.
B0 Lifetime 1.503+/-0.036 ps
good tag
Page 16
sin2f1=+0.68+/-0.06
2015/7/7
0
B K
S
0
p
tCPV Result
“sin2f1”=  0.33  0.35  0.08
A =  0.05  0.14  0.05
good tag
Consistent with
• sin2f1 from bc
• the sum rule expectation
A = 0.150.06
using Belle 532M A, Br and
PDG2006 t+/t0
Page 17
2015/7/7
Summary
• tCPV in bsqq modes are sensitive to the new physics
– “Golden modes” are fK0, h’K0, KSKSKS
• New Results from Belle with 532 M BB
B0h’K0
“sin2f1”=  0.64  0.10  0.04
A =  0.01  0.07  0.05
5.6s tCPV observation
B0KSp0
“sin2f1”=  0.33  0.35  0.08
A =  0.05  0.14  0.05
• Other tCPV results will be reported in the Plenary Talk by
M. Hazumi.
Page 18
2015/7/7
Page 19
2015/7/7
0
B h’K
Page 20
S
DE distribution
2015/7/7
0
B h’K
S,h’KL
Results
“sin2f1”=  0.67  0.11
A =  0.03  0.07
Page 21
“sin2f1”=  0.46  0.24
A =  0.09  0.16
errors are statistical only
2015/7/7
“sin2f1”
Page 22
A
2015/7/7
Systematic Errors
h’K0
KSp0
dS
dA
dS
dA
Vertexing
0.013 0.021
0.011 0.020
Flavor tagging
0.004 0.007
0.008 0.005
Resolution
0.035 0.024
0.066 0.010
Physics
0.001 0.007
0.007 0.001
Possible Fit bias
0.007 0.005
0.009 0.004
BG fraction
0.020 0.022
0.009 0.001
BG dt shape
0.004 0.002
0.046 0.019
Tag-side interference 0.001 0.024
0.001 0.043
---------------------------------------------Total
0.043 0.047
0.082 0.053
Page 23
2015/7/7