The Y5S at CLEO

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The Y(5S) at CLEO
Introduction Bs Reconstruction at the Y(5S)
CLEO PRL 96, 022002 (2006) B Reconstruction at
the Y(5S) CLEO PRL 96 152001 (2006)
Inclusive Ds production at the Y(5S)
CLEO PRL 95 261801 (2005) update CLEO Conf
06-16 Inclusive phi production at the Y(5S)
CLEO Conf 06-16
Ian Shipsey Purdue University For the CLEO
Collaboration
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Introduction

• The Y(5S) discovered by
• CLEO CUSB in 1985.
• massive enough to decay into
• Knowledge of Bs production at Y(5S) essential for
  assessing the potential of Bs physics at a high
  luminosity ee collider.
• A clean source of BS decays is valuable to
  interpret New Physics found directly at the LHC.

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Y(5S) Brief History
CLEO PRL 54 381, 1985

• CLEO CUSB scan in 1985 0.07 fb-1 0.12 fb-1
  taken on peak

Y(6S)?
Y(5S)
CUSB PRL 54, 377, 1985

• CUSB fit to modified
• potential model

But no conclusive evidence for Bs production at
Y(5S)
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Return to Y(5S)

• New Data
• CLEO III 2003 0.42 fb-1 at 10881 MeV
• BELLE 2005 1.86 fb-1 at 10869 MeV (Talk of
  Drutskoy)
• BELLE June 2006 19 fb-1 at 10869 MeV (to be
  analysed)
• Analysis differences between Y(5S) and Y(4S)
• The ratio of resonance to continuum is larger at
  the Y(4S)
• Same continuum data used for both Y(5S) and
  Y(4S). But continuum data is almost 300 MeV in
  CME below Y(5S) and is usually taken at
  different times. So the continuum subtraction
  becomes a significant systematic error
• Cross sections measured in 1985 have been
  re-measured
• CLEO (0.3010.0020.039) nb
• BELLE (0.3050.0020.016) nb
• Excellent agreement

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CLEO Result 1 Observation of the Bs
_at_Y(5S) Exclusive reconstruction of
the Bs

• An extension of B meson reconstruction technique
  used at the Y(4S)

CLEO PRL 96, 022002 (2006.)
MC
Case 1 Case 2 Case 3
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CLEO Result 1 Observation of the Bs
_at_Y(5S)
4 events Y(5S) ? Bs Bs 3 Bs?J/?? , 1
Bs?J/???.
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10 events Y(5S) ? Bs Bs Bs ? Ds() ?/? (4 Ds
modes)
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CLEO Result 2Ordinary B mesons _at_ Y(5S)
MC

• The Y(5S) resonance can decay into a variety of
  states with ordinary B mesons
• 7 possibilities

Use same analysis techniqiue developed for Bs
mesons in previous analysis.
Ordinary B decay modes occupy a different region
on the ?E-Mbc plane have distinct decay modes
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Ordinary B Mesons _at_ Y(5S)
With more BB final states (7) Mbc plane is
slightly more complicated.
B?D()(p or r) B? J/y K()
Data
MC
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Ordinary B Mesons _at_ Y(5S)
1-D projection beam constrained mass with
suitable cuts on DE
CLEO
BB

• Use B?D()(p or r),
• B? J/y K()
• Production largest for BB, consistent with
  models
• BB/BB lt 22 _at_ 90 cl
• BB/BB (2493)
• BS mass
• M(BS)-M(B)(87.61.60.2) MeV
• M(Bs)(5411.7 1.6 0.6) MeV
• M(BS)-M(BS)(45.71.70.7) MeV consistent, as
  expected from Heavy Quark Symmetry with
  
• M(B)-M(B) 45.780.35 MeV

BBpp
BB
BB()p
BB
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Ordinary B mesons _at_ Y(5S)

• Determine yield from
• B?D()(p or r) B? J/y K()
• with B invariant mass
• Total of 539 events
• s0.1770.0300.016 nb,
• 59 of resonance cross section combine with
• the sum s (0.286 0.040) nb saturates (within
  the stats.)
• Compare to total cross section
• Translates to fS0.410.100.10

Invariant mass
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Model Dependent BS Fractions, fS

• Method use inclusive yield
• Choose a particle that has very different decay
  rates from B BS
• Ex DS

measure
measure
Model estimate based on quark level diagrams and
measured ordinary B decay rates ? B(BS?DS X)
(9211)
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Result 4
Measurement of fS from Ds Yields -data
Y(5S) Y(4S)
continuum
Y(4S)
Branching Fraction
Y(5S)
x ( p/Ebeam )
(CLEO)
(Belle)
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Measurement of fS Using f Yields
Result 4

• Here we need B(BS ? fX)
• Use CLEO-c inclusive yields for
• B(Do ? fX)(1.00.100.10)
• B(D ? fX)(1.00.100.20)
• B(DS ? fX)(15.12.11.5)
  Preliminary
  hep-ph/0605134
• From B(B ? fX)(3.50.3), ascertain that most of
  fs arise from B ?D DS?f
• Predict that B(BS ? fX)(14.92.9)

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Measurement of fS Using f Yields -data

• CLEO inclusive f yields, for xlt0.5, R2lt0.25

Y(5S) Y(4S)
Branching Fraction
x ( p/Ebeam )
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Measurement of B(Y(5S) ? BS()BS ()) Using DS
f Mesons
SUMMARY
s(ee- ? Y(5S)) (0.301 0.002 0.039)nb
1 CLEO PRL 95, 261801 (2005) 2 CLEO PRL 96
152001(2006)
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Summary of fS Measurements
Combine with Belle

• Plot statistical systematic uncertainties
  added linearly
• Average takes into account correlated syst.
  uncertainties on Y(5S) cross-section
• model dependencies on Inclusive yields

Plot adapted form Stone SuperB Workshop SLAC
6/2006
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Summary

• 1st Observation of the Bs at the Y(5S)
  and determination of the composition of BsBs
  final states. BsBs dominates
• 1st determination of the composition of ordinary
  BB final states at Y(5S). BBBBBB 31lt1,
• Upper limits for BB ,B()B()p and BBpp, BsBs
  BsBs.
• Both Bs B compositions consistent with
  predictions
• M(Bs)(5411.7 1.6 0.6) MeV world best
  measurement.
• M1 Mass splitting M(BS) - M(BS) (45.7 1.7
  0.7) MeV
• as expected by HQS
• Inclusive yields of Ds and phi mesons measured
  for the first time ?
• Bottom line between about ¼ (0.07 nb) 1/3
  (0.11 nb) of Y(5S) decays
• to BS() BS() These estimates are model
  dependent and indicate that an
• extended Y(5S) run at a B factory would be
  fruitful.
• Belle results from 1.8/fb run are in broad accord
  with the above results

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Additional Slides
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Result 3
Y5S
Y4S
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Comparisons with Models
Unitarized Quark Model
Quark Hybrid Model

• UQM predicts DR0.4, fS38, BSBS large
• QHM predicts DR0.7, fS21, BSBS large
• Other models
• Martin Ng, Z Phys. C 40, 133 (1988)
• Byers hep-ph/9412292

Y(5S)
Y(5S)
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Model of DS Production

• Must assume knowledge of B(BS?DS X)
• Account for fragmentation that reduces DS rate
  from BS, CLEO BELLE use same model B(BS?DS X)
  (9211)