Results from the CLEO-c Ds Scan

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Results from the CLEO-c Ds Scan
Ron Poling CLEO Collaboration and University of
Minnesota
IHEP/Beijing June 7, 2006
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Topics

• D and Ds production
• Ecm3970 4260 MeV
• CLEO studies of the Y(4260)

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The CLEO-c Charm Program

• Direct CKM measurements, theoretical tests and
  indirect CKM measurements, engineering input to
  other heavy-flavor experiments.
• D0 and D leptonic, semileptonic, hadronic decays
  at ?(3770).
• Ds leptonic, semileptonic, hadronic decays at
  some energy.
• The CLEO-c project description stated

• we will scan the center-of-mass energy region
  between 3.77 and 4.22 GeV to determine the cross
  sections for the various final statesto
  determine the optimum energy for Ds production

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CLEO-c Scan Run ECM 3970-4260 GeV

• Primary Motivation
• Determine optimal energy for Ds
• ??BF(Ds???)11 pb (DsDs-)
• from BES at 4040 MeV
• ??BF(Ds???)26 pb (DsDs -)
• from Mark III at 4140 MeV

• Additional Objectives
• Detailed study of hadronic cross section above
  open-charm threshold.
• Y(4260) confirmation, more details.
• Assess capabilities for D physics above ?(3770).

• Scan Data Sample
• 12 energies, 60 pb-1
• First real Ds Run at 4170 MeV
• Part 1 76 pb-1 results in other talks at CHARM
  2006
• Part 2 200 pb-1 in hand, results in summer 06
• Part 3 more to come

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Reconstruction Strategy
?(3770)
Adapted from ?(3770) technology....

• For scan studies 3 D0, 5 D, and 8 Ds modes to
  select charmed mesons.
• Identify event types based on differences in
  momentum (?Mbc) and ?E.

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Measure Cross Sections for 8 Event Types
Monte Carlo ECM4160 MeV

• For DD and DsDs cut on ?E and use Mbc to extract
  yields.
• For other event types cut on Mbc and use
  invariant mass to extract yield.
• Cut values determined by kinematics no double
  counting allowed, cross-feed small and calculable.

D?D0?
D0?D0(?,?)
D?D0?
D0?D0(?,?)
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Closer look selecting Ds
Monte Carlo ECM4160 MeV
Ds??? from various final states
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Complication Not all charm events fall into one
of the 8 final states, with two charmed mesons
and nothing else.Evidence for multibody (MB)
events, e.g. ee-?DD?
D0 Momenta
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PRELIMINARY
Partial systematic uncertainties Multibody
correction not applied Not radiatively corrected
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PRELIMINARY
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Cross-Check Inclusive vs. Exclusive
Partial systematic uncertainties Not radiatively
corrected
PRELIMINARY

• Exclusive
• Sum of (up to) 8 modes with two
• charmed mesons (no MB)
• Inclusive charm
• D0 D Ds
• Inclusive Hadrons
• Excess over uds

Good agreement between two inclusives. Excess of
inclusive over exclusive reaffirms MB.
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• Scan Conclusion
• Ds Mini-Factory at ECM4170 MeV has been
  identified.
• ?(DsDs) ? 1 nb
• Precise value depends on Ds branching fractions
  (PDG so far, but CLEO-c soon).
• Lots of results from first 76 pb-1 for the Ds
  program, some of which you have already seen.

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Y(4260) BaBar PRL 95, 142001 (2005)

• One of several new states in the charmonium
  region that dont quite fit in.
• X(3872), X(3940), Z(3930), Y(4260)

ee-???ISRY(4260) Y(4260)??p-J/? At a dip in R!
s(ee-??p-J/?)50 pb
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CLEO III sees it too Preliminary
ISR ?(1S)-?(4S) 13.3 fb-1
Consistent results
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Y(4260) hybrid charmonium, hadronic molecules,
baryonium, tetraquark, conventional charmonium

• What can CLEO-c say?
• Confirmation via direct ee- production.
• ECM4260 MeV point added to scan program after
  main goal was accomplished 13.2 pb-1.
• Broad search for many possible final states.
• 16 final states ??-J/?, ?0?0J/?, KK-J/?, other
  J/?, ?(2S), ?cJ, ? modes
• Built-in calibration mode ee-???(2S)???-J/?
  , ?0?0J/?, ?J/?

uncertainty in BaBar meast
?
?
Y(4260)
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Charmonium Decays of ?(4040), ?(4160), and Y(4260)
CLEO-c PRL 96, 162003 (2006)

• Y(4260)???-J/? confirmed (11?)
• First observation of Y(4260)??0?0J/? (5.1?) and
  first evidence for Y(4260)?KK-J/? (3.7?).

Observations so far do not greatly narrow the
possible explanations. ?cJ molecular states
appear to be disfavored, as does conventional
charmonium proposal Y(4260)? 4S. Real
clarification will require open-charm
measurements - tough with current data sample
(13.2 pb-1).
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Conclusions

• The CLEO-c Ds scan
• Optimal energy for Ds 4170 MeV.
• Experience in Ds/D physics with mixture of final
  states.
• Detailed measurements of charm production in
  threshold region analysis in progress.
• Y(4260) confirmation, additional information to
  aid interpretation.
• Potential to disentangle open-charm production
  with D momentum spectra and other observables
  especially for high-statistics samples (4170 MeV).

Preliminary
5 times at Charm 2006!

• CLEO-c plan through April 08
• 750 pb-1 at ?(3770) for D physics, 750 pb-1 at
  4170 MeV for Ds (and D) physics and 30 million
  ?(2S).