Status of Vub from Belle

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Status of Vub from Belle
Youngjoon Kwon Yonsei University for the Belle
collaboration
Course

• Appetizer W-annihilation modes with Vub vertex
• Entree decay modes that we (can) use to measure
  Vub
• Dessert to finish with something sweet

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The Unitarity Trianlge
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W-annihilation decays with Vub vertex

• A

• The cleanest mode with Vub vertex is fully
  leptonic B decays

• uncertainty in fB
• BF is very small for
• (helicity suppression)
• or experimentally very messy due to multiple
  neutrinos for
• a good place to search for new physics

4

• A

Belle-CONF-0247
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Results

• A

Belle-CONF-0247
Preliminary

• Fitting pl distribution
• no evidence of signals gt 90 CL upper limits

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Semileptonic B decays for Vub

• E0

• Semileptonic B decays provide the best
  opportunity for measuring Vub
• - strong interaction effects are much simplified
  due to the two leptons in the final state

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Vub from

• E1

• use detector hermeticity to measure undetected
  neutrino
• the events should be consistent with
• hermeticity assumption
• Qtotal lt 2 only one IDed lepton
• only one missing neutral particle neutrino
• attribute missing (E,p) to the neutrino

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• E1

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BF( ) Vub

• E1

Preliminary
(Khodjamirian et al.)
PRD 62, 114002 (2000)
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q2 distribution of B ? p l n

• E1

preliminary
Unfolding of true q2 distribution from observed
distribution, by considering efficiency/smearing
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• E2

Belle-CONF-0242
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• E2

Belle-CONF-0242

• N(events) in the signal region
• with 0.76 lt m(3p) lt 0.81

MC est.
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• E2

Belle-CONF-0242

• Systematic uncertainties
• background est. 18.0
• signal fitting 9.2
• MC statistics 5.1
• tracking 6.0
• photon-finding 4.0
• electron ID 3.0
• Total 22.3

preliminary
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• E3

• Similar neutrino reconstruction
• using hermeticity
• 2-dim. fit to DE vs. M(pp)

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• E3

• Tentatively, using ISGW2 for
• - efficiency, hence BF and
• - Vub

• Projections onto DE and M(pp)

preliminary
16

• D

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• D1

Belle-CONF-0248
preliminary
We also have
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• D1

preliminary

• Using PDG2002 for Vcb,

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• D2

Belle-CONF-0247

• back to W-annihilation decay with Vub vertex
• same 3 Ds decay modes

preliminary
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Conclusion (1)
preliminary
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Conclusion (2)
preliminary
UKQCD
Khodjamirian, et al. (LCSR)

• From new measurement of
• and using factorization-based calculation

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Backup slides
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The KEKB Collider

• asymmetric energy
• e (3.5 GeV) e- (8 GeV)
• design Luminosity 1034 /cm2/s
• E(cm) 10.58 GeV on resonance of ?(4S)
  production

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The Belle detector