New CP Violation Results from B-meson Decays at Belle

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New CP Violation Results from B-meson Decays at
Belle
Yee Bob Hsiung National Taiwan University

• December 1, 2004

????Physics Colloquium
_at_
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What is CP Violation?
CP Violation or Matter-Antimatter asymmetry
C charge conjugation P space inversion T
Time reversal
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Why Studying CP Violation?
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CP Violation in the Standard Model

• CP violation (e) was first discovered in Kaon
  decays (1964)
• 33 years later (1997) direct CP violation was
  observed in K to 2p decays (e/e)
• CP violation in the B decays can now be studied
  in both Belle(KEK) and BaBar(SLAC) in detail

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Cabbibo-Kobayashi-Maskawa Matrix
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CP-Violation in Standard Model
A phase in the quark-quark current leads to
CP-Violation (Kobayashi, Maskawa, 1973)
Ng3 Nphase1 ? CP-Violation Possible
6 unitarity relations ( triangles in the complex
plane)
JCP2?(Triangle Area) Is the unique measure
of CP-Violation in SM
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Wolfenstein Parametrization
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CP Violating Phase
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The Kaon System
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NA48
_at_ CERN Fermilab
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Direct CP Violation
DS 1
Penguin Diagram
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Direct CP Violation Re(e/e)
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Kaon Decays and the SM
KL to 2p e/e
CP-Violation
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The Unitarity Triangle
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The Unitarity Triangle
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(No Transcript)
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The B Factories KEKB and SLAC-PEPII
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???????????!
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KEK (???????) ???
???
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253 fb-1 on Y(4S) 28 fb-1 below Y(4S)
KEKB ??????
8 GeV electron
3.5 GeV positron
??
???
KEKB Collider
275M BB
Lpeak 1.39 x 1034 sec-1cm-2
_at_ 1.2A x 1.6A
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The Billion Question ??B???CP??

B??????????
Red Hot !
2001
J/yKS, pp-, hKS, fKS
One B Decay CP Eigenstate Other B Decay Tag
Flavor Measure Both Decay Vertex
??????
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Belle Detector
Aerogel Cherenkov cnt.
n1.0151.030
SC solenoid 1.5T
3.5 GeV e
CsI(Tl) 16X0
TOF conter
8 GeV e-
Central Drift Chamber small cell He/C2H5
Si vtx. det. 3(4) lyr. DSSD
m / KL detection 14/15 lyr. RPCFe
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B-meson Reconstruction
Utilize special Kinematics at Y(4S)
Energy difference

Beam-constrained mass
(ES)
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Continuum Suppression
Dominant Background for rare decays
Continuum
ee- ? qq continuum (3x
BB)
Jet-like
To suppress use event shape variables
BB
spherical
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SVD Upgrade
2003 summer
Impact parameter resolution
rf
Z

• 1 MRad ? gt20 MRad
• 3 layers ? 4 layers
• 23ºltqlt139º ? 17ºltqlt150º
• Rbp 2.0 cm ? 1.5 cm
• Better I.P. resolutions

_
_
152M BB pairs with SVD1 123M BB pairs with
SVD2
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Belle SVD2 Upgrade
NTU Contribution TTM Trigger Timing Module
SVD2 under construction Install Summer 2003
FPGAs
From 3-layers of SVD1 to 4-layers
self-tracking
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Students!
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SVD2 lifetime Dmd
SVD2 only
D0p, J/y K? ,
Dp, Dp/r, Dln
Belle preliminary
SVD1 _ (152M BB)
SVD2 _ (123M BB)
(stat)
ps
(stat)
ps
(stat)
ps-1
Belle-conf-0436
New detector resolution is well understood
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B ? Kp/pp
Tree
Penguin

• Simplest charmless rare decay modes
• Tree - Penguin interference ? Direct CP Violation

Key prediction of Kobayashi-Maskawa model
Understanding of Penguin
Anomaly (New Physics)
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ACP(B0 ? Kp-)
_ B0? K-p
B0? Kp-
Signal 2139 ?53
submitted to PRL
ACP -0.101 ? 0.025 ? 0.005
3.9s significance
PID efficiency bias correction dA -0.01 ?
0.004
2nd Evidence for DCPV at Belle ! A(pp-) 3.2s
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B0 g pp? CPV Result
Direct CPV ?3.2s
good tag
Dt (ps)
App 0.58 ?0.15(stat) ?0.07(syst) Spp ?1.00
?0.21(stat) ?0.07(syst)
PRL93,021801 (2004)
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ACP(B ? Kp0 )
K?p0 728 ?53
ACP(K?p0 ) 0.04 ? 0.05 ? 0.02
hint that ACP(Kp- ) ¹ ACP(K?p0 ) ? (2.4s)
d
p0
Large EW penguin (Z0) ? New Physics ?
_ d
B-
s
b
K-
u
u
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Observation of B0 ? p0p0
Key mode for f2(a) in B g pp CPV isospin
analysis
Evidence (LP03) ? Observation !
Signal 82 ? 16 (6.0s)
B (2.32 ? ? ) x 10-6
0.44 0.48
0.22 0.18
Large Br established
Mbc
Belle-conf-0406
ACP 0.44 ? 0.51 ?
0.17 0.16
uses same Flavor-tagging as TCPV analysis
1st measurement !
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Radiative EW Penguins
Loops ? Sensitive to New Physics
l
l-
b ? sll- penguin
1/100
b ? sg penguin
Br, ACP SM
b ? dg penguin
Kg TCPV
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B ? K() ll-
Belle-conf-0415
LP03 B ? Xsll, K()ll Belle/BaBar
Br, ACP SM
update
gt10s signals
82 ?11 signals
79 ?10 signals
B (Kll) (5.50 ? ? 0.27 ? 0.02)
0.75 0.70
B (Kll) (16.5 ? ? 0.9 ? 0.4 )
2.3 2.2
x 10-7
Mbc
q2 (GeV2/c2)
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Time-dependent CP Violation
(TCPV)
B0
fCP

fCP
B0
mixing
B0
B0
ACP (Dt) S sin(DmDt) A cos (DmDt)
Mixing induced CPV
Direct CPV
f

New Physics with New Phase
SM b? s Penguin phase J/yKS (b? c)
Sb?s ¹ sin2f1 , A can ¹ 0
Sb?s sin2f1, A0
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Time Dependent CP Asymmetry
S -xf sin2f1 SM prediction
A 0 or l 1 ? No direct CPV
Af
q
l hf
CP
p
Af
CP
Inputs xf -1, S 0.6 A 0.0
CP
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b ? sqq Penguin CPV
-
Belle _at_LP03 (140 fb-1)
PRL 91, 261602 (2003)
B0? fKs
B0? J/yKs etc
sin2f10.728 ? 0.06
sin2f1 -0.96 ? 0.51
3.5s deviation from the SM !
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B0 ? f K0
fKS
Nsig139 ?14
fKL
purity 0.63
Nsig 36 ?15
purity 0.17
Similar to J/yKL recon. sophisticated continuum
suppression
includes Ks ? p0po (Nsig13 ?5)
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B0 ? f KS Mass Helicity
f Helicity
Mass
bkg
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B0 ? f K0 CPV Result
f K0
Good tags
Poor tags
Good tags
fKS fKL S (fK0) 0.06 ? 0.33 ? 0.09
A (fK0) 0.08 ? 0.22 ? 0.09
2s away from SM
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Checks sin2f1 (B0 ? J/y KS/L)
Validation of new data sample (SVD2)
_
SVD1 152M BB
SVD1
S 0.696 ? 0.061 (stat) A 0.011 ? 0.043 (stat)
Good tags
_
SVD2 123M BB
SVD2
S 0.629 ? 0.069 (stat) A 0.035 ? 0.044 (stat)
Good tags
Dt (ps)
f K0
2.3s
SVD2 S 0.78 ? 0.45 A 0.17 ? 0.33
SVD1 S -0.68 ? 0.46 A -0.02 ? 0.28
many systematic checks, all ok
?
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History of sin2f1 with fK0
_ sin2f1 from ccs
sin2f1
BABAR
Belle
?106
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B0?hKS KK-KS
high statistics modes
hKS
KK-KS
(f excluded)
h? rg, hpp- (h? gg, pp-p0)
Nsig399 ?28
Nsig512 ?27
purity 0.56
purity 0.61
CP1 1.03 ?0.15 ?0.05
Raw Asymmetry
Raw Asymmetry
Good tags
Good tags
sin2f1
(0.5s _at_SM)
(1.0s _at_SM)
S 0.65 ?0.18 ?0.04 -S 0.49 ?0.18
?0.04 (? ) A -0.19 ?0.11 ?0.05 A
-0.08 ?0.12 ?0.07
0.17 0.0
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B0?wKS f0(980)KS
wKS
f0(980)KS
additional modes
Nsig31 ?7
Nsig94 ?14
purity 0.53
purity 0.56
Raw Asymmetry
Raw Asymmetry
Good tags
Good tags
sin2f1
(2.9s _at_SM)
(0s _at_SM)
S 0.75 ?0.64 ? -S -0.47
?0.41 ?0.08 A 0.26 ?0.48 ?0.15 A
-0.39 ?0.27 ?0.08
0.13 0.16
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Summary of b ? sqq CPV
-
sin2f1
2.4?
(A consistent with 0)
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Charmless B Br Summary
HFAG P.Chang (NTU) J.Alexander (Cornell)
J.Smith (Colorado)
Complete list (other Br ACP )
http//www.slac.stanford.edu/xorg/hfag/rare/
x10-6
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Summary

• CP Violation has been well established in the
  kaon system, both direct and indirect and now
  being extensively explored in B-meson system
• Evidence of direct CP violation has been seen
  in
• B0 ? Kp- (-10), search for new physics beyond
  the Standard Model will continue in b?s penguin
  modes and 3 angles measurement of unitarity
  triangle.
• However, the origin of CP violation may well be
  uncovered from both K and B system in the next
  5-10 years by comparing the (in)consistency of
  the unitarity triangles
• There maybe hints of new physics beyond the SM in
  the K and B system which will call for high
  luminosity (1036 SuperB) machine, better
  experiments at JHF-JPARC and new physics
  studies/searches in the LHC and/or LC era

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Future Prospect of f1 (b) Measurements
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Future Prospect of f2 (a) Measurements
0.5 ab-1
5 ab-1
50 ab-1
Going for Super B factory
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The End