Time-Dependent CP Asymmetries in b?s Penguins

1
Time-Dependent CP Asymmetries in b?s Penguins
PANIC05_at_Santa Fe
Hideki MIYAKE (Osaka Univ.)
Belle collaboration
Oct. 24-28th, 2005 Santa Fe, NM, U.S.A.
2
Outline

• Introduction
• TCPV in b?s penguins at Belle
• b?sqq decays
• b?s? decays
• Summary

These are very HOT topics!
3
Introduction

• TCPV measurements in B0 decays

b?ccs
b?sqq
_
w
J/Y
s
?,f
g
t
B0
B0
s
_
s
K0
K0
d
Check if
sin2f1 0.65, A 0
/
sin2f1 -?fS sin2f1, A 0
Extra CPV phase sin2f1?sin2f1 Hint of New
Physics
SM Anchor
4
Experimental technique

• Same as sin2f1 measurement

f
K
K-
z
Dt(zrec -ztag)/cbg
Time-Dependent CP Violation Parameters
5
b?sqq decays

• We measured following b?sqq decays
• B0?fK0
• B0??K0
• B0?KK-KS
• B0??KS
• B0?f0(980)KS
• B0?KSKSKS
• B0?KSp0

?f (CP eigen value)
-1(KS) or 1(KL) -1(KS) or 1(KL)
mixture -1 1 1 -1
KS vertexing
?Each analysis outline will be shown at the
following part
6
B0?fK0 decays

• B0?fK0K0KS or KL

B0?fKS (KS?pp-,p0p0)
386M BB pairs
Preliminary
Nsig180?16 Purity 0.57
7
B0?fK0 decays (contd)
B0?fKL
BG subtracted
Preliminary
Nsig78?13 Purity 0.12
Combined KL selection and continuum suppression
variables
8
TCPV in B0?fK0 decays
fK0 combined result
fKS

• fKS
• fKL

BG subtracted
Good tags
S0.19?0.32 A -0.12?0.20
Preliminary
fKL
Good tags
S -1.54?0.59 A0.38?0.36
sin2f10.44?0.27?0.05
A 0.14?0.17?0.07
9
B0??K0
?KS

• ?KS
• ?KL

S0.60?0.14 A -0.04?0.09
Good tags
Nsig830?35 Purity 0.61
Preliminary
?KL
Nsig187?17 Purity 0.26
S -0.73?0.29 A-0.02?0.18
Good tags

• ?K0 combined result

sin2f10.62?0.12?0.04
A -0.04?0.08?0.06
BG subtracted
10
B0?KK-KS

• Mixture of CP-even and -odd

Preliminary
Good tags
S-0.52?0.16?0.03 A-0.06?0.11?0.07
Nsig536?29 Purity 0.55
f(?f1)0.930.090.05
0.19 - 0.12
sin2f10.60?0.18?0.04
11
B0??KS
Preliminary
Nsig6813 Purity 0.17
Good tags
sin2f10.95?0.53
A
0.19?0.39?0.13
0.12 - 0.15
12
B0?f0(980)KS

• Peaking BG from pp-KS

f0Ks
Preliminary
Nsig145?16 Purity 0.42
Good tags
sin2f10.47?0.36?0.08
A 0.23?0.23?0.13
13
B0?KS KS KS

• KS vertexing

Good tags
Preliminary
Nsig105?12 Purity 0.64
sin2f10.58?0.36?0.08
A 0.50?0.23?0.06
14
B0?KSp0
Ks track
p p-
?
?

• Yet another KS vertexing

IP profile
B vertex
Good tags
Preliminary
Nsig344?30 Purity 0.25
sin2f10.22?0.47?0.08
A 0.11?0.18?0.08
15
sin2f1 from b?sqq
Deviation from the SM lt1s
16
b?s? decays

• SM CPV suppression due to ? polarization

g
s
L
Due to g, the final state is (almost) flavor
specific
(Helicity flip)
b
g
s
R
2
m
f

Sin2 4
s
S

1
CP
m
b

• Large CPV implies New Physics

17
B0?Ksp0?
Preliminary
Good tags
Nsig115?16 Purity 0.54
sin2f10.08?0.41?0.10
A 0.12?0.27?0.10
M(KSp0)lt1.8GeV/C2

• No indication yet of new physics from right
  handed currents

18
Summary

• Search for new physics phases with b?sqq hadronic
  penguins
• B0?fK0
• B0??K0
• B0?KK-KS
• B0??KS
• B0?f0(980)KS
• B0?KSKSKS
• B0?KSp0
• New measurement with b?s? radiation penguin
• B0?KSp0?

386M BB

• No significant deviations with SM expectation

?Need more statistics!!
19
Backup
20
b g u pollution
mode ?CP P P T T
fKs -1 ? ? ? ?
KsKsKs 1 ? ? ? ?
KK- Ks 1 ? ? ? ?
h?Ks -1 ? ? ? ?
f0(980)Ks 1 ? ? ? ?
wKs -1 ? ? ? ?
p0Ks -1 ? ? ? ?
fKs and KsKsKs are two golden modes for the future
rescattering ignored
21
fK0 experiment dependence
22
275M BB results
B0?KK-K0
B0?fK0
Poor tags
Poor tags
Good tags
Good tags
23
Toy MC Pull, Error
B0?fK0
B0?KK-K0
24
Determination of f
PDG2005 tB0/tB 1.071 - 0.009
25
B0?KK-KS CP ?1 Mixture
Since B0 ? KK-KS is 3-body decay, the final
state is a mixture of CP ?1. How can we
determine the mixing fraction?
CP ?1 fraction is equal to that of leven/odd
CP 1
CP 1
K
J0
J0
J0
decay
l
KS
B0
CP (-1)l
l
K-
J0
26
Determination of CP1 Fraction

• l-even fraction in K0K0gt can be determined by
  KSKSgt system
• Add K to above kets

CP 1
l odd
l even
Using isospin symmetry,
27
WA incl. Babar
There is 2.6s discrepancy (w/o
theoretical/experimental correction )
28
KS vertexing with J/yKS
For BgJ/yKS? both B vtx (w/ KS)?B vtx (w/ J/y)
are available
l l -
p p-
Ks
B vertex
IP profile
W/J/y
raw asymmetry in BgJ/yKS (KS vertex)
SJ/yKs 0.668?0.047 AJ/yKs -0.021?0.034
preliminary
Poor tag
W/KS
SJ/yKs 0.732?0.080 AJ/yKs 0.014?0.037
Consistent results
Good tag
29
KS vertexing
Resolution function is decided from same PDF as
J/yKs with floating B lifetime
tB01.55?0.05(ps)
?Ks vertexing works!
30
b?s?AGHS
New Idea
SM CPV is suppressed in b?Xsg with any Xs, ex)
K0g? K20g?and B?KSp0g
AGHS Phys. Rev. D 71, 076003 (2005)
10 asymmetry comes from strong phase?
GGLP Phys. Rev. D 71, 011504 (2005)
Anyway?we measure K0 modes and non-K0 modes!
Mass region1 M(KSp0) lt 1.8GeV Mass region2 0.8 lt
M(KSp0) lt 1.0GeV
KSp0g K0(gKSp0)g
31
b?sprevious results
PRL 93, 201801 (2004)
PRL 94, 231601 (2005)
PRL 94, 231601 (2005)
32
B0?KSp0g
33
TCPV in B?FK0 decays
fKS
fKL
Good tags
Good tags
S -1.54?0.59 A0.38?0.36
S0.19?0.32 A0.12?0.20
34
B0?fK0 combined result
BG subtracted asymmetry
fK0
sin2f10.44?0.27?0.05 A
0.14?0.17?0.07
b?ccs World Average sin2f10.687?0.032
35
B0 ? h KS0
Nsig 83035 Purity 61 CP odd
Best for FoM S/sqrt(SB)
h?h p p- r g
Belle preliminary
36
B0 ? h KL0
Because P(KL0) cannot be measured, S/N is much
lower than KS0 mode. In case of low S/N mode,
much signals are rejected if we optimize the
selection by
Bkg
signal
Likelihood ratio (lhr)
Number of events are increased if we use
likelihood ratio distribution itself.
37
Observables for TCPV
CP Violation manifests itself in proper-time
difference (Dt) distributions of two B meson
decays.
ACP
S sin(DmDt) A cos (DmDt)
Direct CPV
Mixing induced CPV
(BaBar A -C)
38
Flavor Tag
NIM A 533, 516 (2004)
39
Wrong tag probability
NIM A 533, 370 (2004) for resolution
Estimate w from time-dependent B0-B0 mixing
40
Kobayashi-Maskawa Phase
l 0.22
CP violation is due to a complex phase in quark
mixing matrix
CP violation parameters (f1, f2, f3) (b, a, g )
41
sin2f1 measurement
Vtd
Vtd
A0
xCP CP eigenvalue, 1 (-1) for CP even (odd)
We can measure CPV (asym.) as a function of
proper time diff.
42
Principle of TCPV measurement
CP-side
m
J/y
m-
?(4S) resonance
B1
electron (8GeV)
KS/L
B0
positron (3.5GeV)
nm
B2
p-
bg 0.425 (Belle) 0.56 (BaBar)
K
p-
Flavor tag and vertex reconstruction
Dz 200mm (Belle)
m

1. Fully reconstruct one B-meson which decays to CP
   eigenstate
2. Tag-side determines its flavor
3. Proper time (Dt) is measured from decay-vertex
   difference (Dz)

43
KEKB the highest luminosity in the world
KEKB
PEP-II
3.5 GeV e ? 8.0 GeV e- ee- ? ?(4S) with bg
0.425 22 mrad crossing angle
_
386 M BB pairs analysis are shown, today
44
Belle Detector
K/p separation

• , p0 reconstruction
• e-, KL identification

Aerogel Cherenkov Counter n 1.0151.030
Electromagnetic Calorimeter CsI(Tl) 16X0
3.5 GeV e
TOF counter
K/p separation
charged particle tracking
8.0 GeV e-
Central Drift Chamber momentum, dE/dx
50-layers He/C2H6
B vertex
Muon / KL identification
Si Vertex Detector 4-layer DSSD
KL m detector 14/15 layer RPCFe
45
CP violation in B0 decays
f
1
Interference between 2 decay diagrams are raised
by CP phase in B0-B0 mixing
B0
B0
?
Mixing induced CP violation
B0?fCP?B0?fCP
Direct CP violation
46
CP violation in B0 decays
S
A
S
?t
Time-asymmetric
Proper time difference ?t
A
?t
Time-symmetric