Penguin Dominated CP Violation, DCPV and Search for New Physics

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Penguin Dominated CP Violation, DCPV and Search
for New Physics
Yee B. Hsiung, National Taiwan University ? 5th
Rencontres du Vietnam ? Hanoi, 6-11th August 2004

• Introduction to Penguin
• Radiative Penguin Decays
• DCPV
• Status Perspective

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CP Violation by Kobayashi-Maskawa
KM ansatz CP violation is due to complex phase
in quark mixing matrix
unitarity triangle
CP violation parameters (f1, f2, f3) (b, a, g)
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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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New Physics Hunting in b ? sqq
SM predicts same CPV in b ? ccs and sqq.
New physics may deviate CPV in b ? ccs from sqq
New process w/ different CP phase
SM penguin

e.g.) squark penguin
Deviation from b ? ccs
Hint of new physics !
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Tree vs Penguin
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The KEK-B Collider
3.5 GeV e on 8 GeV e-
L gt (1.3 x 1034)/cm2/sec
? L dt 286.8 fb-1
Y(4S)
274 M BB pairs!
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The Belle Detector _at_KEK
Aerogel Cherenkov Counter
? and KL detection system
3.5 GeV e
3 layers Silicon Vertex Detector ? 4 layers
Electromagnetic. Cal.(CsI crystals)
8 GeV e-
Central Drift Chamber
1.5T SC solenoid
ToF counter
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The BaBar Detector _at_SLAC
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CP Violation in b ? ccs
5417 events _at_ 152M BB
poor flavor tag
Small systematic uncertainty ? Well controlled
analysis technique
fine flavor tag
consistent with no Direct CPV
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b ? sqq Reconstructions

• B0 ? fKS f ?KK?, KS ? pp?
• Minimal kaon-identification requirements.
• Belle standard KS selection.
• M(KK) ? M(f) lt 10MeV/c2 (mass resolution
  3.6 MeV/c2).
• pf in CMS gt 2.0 GeV/c.
• Belle standard continuum suppression.
• DE lt 60MeV, 5.27 lt Mbc lt 5.29 GeV/c2.

M(KK) GeV/c2

• Background is dominated by continuum
• CP in the background
• KK-KS (7.21.7)
• f 0(980)KS
• These effects are included in the systematic
  error.

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CP Violation in b ? sqq
_at_ 152M BB
68?11 signals 106 candidates for S and A
fit purity 0.64?0.10 efficiency 27.3
B 0 ? fKS
199?18 signals 361 candidates for S and A
fit purity 0.55?0.05 efficiency 15.7
B 0 ? KK-KS
B 0 ? h?KS
244?21 signals 421 candidates for S and A
fit purity 0.58?0.05 efficiency 17.7 (h?
hpp?) 15.7 (h? rg )
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CP Violation in b ? sqq
Fit sin2f1

_at_ 152M BB
B0 ? fKS
B0 ? KK-KS
B0 ? hKS
B ? fCP(sqq) decay vertices are reconstructed
using K- or p- track pair.

-xf S

A
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Statistical Significance
B0 ? KK-KS, hKS Consistent with sin2f1. B0 ?
fKS 3.5s deviation (Feldman-Cousins). S(fKS)
sin2f1 0.05 probability.
Hint of new physics? Need more data to establish
conclusion.
Smoking gun?
K. Abe et al. Belle collaboration, PRL 91,
261602 (2003)
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Summary of sin2f1 (b)
3.5s
2.4s
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Another smoking gun?
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Comparing with B ? rr0
100 longitudinally polarized
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Radiative Penguin Decays
b -gt sg and b -gt sll- decays proceed via flavour
changing neutral current (FCNC) box and penguin
diagrams
b -gt sg penguin
BR(b-gtsg) ? 3.5 ? 10-4
Not so rare actually
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b -gt sll- penguin
b -gt sll- box

BR(b-gtsll-) ? aem?BR(b-gtsg) ? 10-6 !!!
New particles can/will contribute quite
significantly to the decay rates and various
asymmetries quite significantly via the
loops! gt Ideal testing ground for SM and
extensions (2HDM, MSSM, GUT, ?)
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Radiative Penguin Results
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BR(B -gt XSll )
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BR(B -gt XSll )
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BR(B -gt XSll )
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Check MXs and Mll mass
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ACP(B -gt Kg )
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Update ACP(B -gt Kg )
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b-gtsg Photon Energy Spectrum
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Search for b-gtdg
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BaBar Results on b-gtdg Search
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Belle Results on b-gtdg Search
More in Parrallel session
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There are lots of them
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Direct CP Violation in pp/Kp
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Direct CP Violation in pp
3.2s DCPV
PRL 93, 021601 (2004)
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ACP in Charmless B Decays
World average
Acp(Kp-)
-0.095?0.028
Hint of DCPV?
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More ACP in Charmless B Decays
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BaBars new ACP for Kp-
new BaBar
4.2s
Acp(Kp-)
-0.133?0.030?0.009
B. Aubert et al.,hep-ex/0407057
2.4s
Acp(Kp-)
-0.088?0.035?0.013
Belle
Y. Chao et al.,hep-ex/0407025
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Status and Prospect

• Smoking gun results in Penguin dominated
  processes, such as
• B0 ? f KS and B0 ? f K have been around the
  corner.
• More data is needed to clarify the situation.
  ? But soon we shall find out the answer.
• Radiative Penguin decays are ideal testing ground
  for SM and new physics. However, no smoking gun
  yet!
• Need more data to fix some of the important
  parameters inEW/radiative penguin transitions
• Direct CP Violation in B-decays may surface very
  soon.
• Many interesting discoveries are still ahead

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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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