New States Containing Charm at BABAR

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New States Containing Charm at BABAR

• PHENO 06 Symposium
• A.J. Edwards - Stanford University
• May 15

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Outline

• ?c(2940)
• A new charm baryon above the Dp threshold.
• ?cc and ?cc
• Are double-charm baryons among us?
• DsJ(2317) and DsJ(2458)
• An update on newly discovered cs states that
  contradict theoretical predictions for mass.
• X(3872) and Y(4260)
• New charmonia?

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?c(2940)
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Charm Baryon Spectroscopy
?c(2940)

• Two new observations in cc continuum of particles
  with decays to D0p
• The first observation of ?c(2880) ? D0p
• Discovery of ?c(2940) in the same decay mode

?c(2880)
D0p Threshold
p
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?c(2940)
hep-ex/0603052
?c(2880)
?c(2940) M (2939.81.31.0) MeV/c2 G
(17.55.25.9) MeV
?c(2940)
?c(2880) M (2881.90.10.5) MeV/c2 G
(5.81.51.1) MeV
Wrong sign D0p
D0 mass sidebands
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?c(2940)
hep-ex/0603052
Sascha Migura et al.

• Three different spin-parity states predicted
  around a mass of 2940 MeV/c2 (1/2), (1/2), and
  (3/2).
• The ?c(2880) is near a predicted (3/2) state.

No significant branching fraction to ?cpp is
observed for ?c(2940). No known reason for the
suppression.
No Sc iso-partner states found in Dp spectrum.
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Doubly Charmed Baryons
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Doubly Charmed Baryons

• Theoretically ?cc Occ should exist.
• The SELEX experiment (hyperon beam) reports
  evidence for them. (1,630 ?c)
• The FOCUS experiment (photon beam) sees no
  evidence for them. (19,500 ?c)

Strangeness
Can they be found at BABAR?
Phys.Lett.B62818-24,2005

• Large numbers of single charm baryons.
• 600,000 ?c and 12,000 ?c0
• Double charm baryon ee cross section
  predictions 1 - 250 fb
• Theoretical branching fractions
• ?cK-p, ?cK-pp, ?c0p, ?c0p-p a few
  percent

SELEX sees an excess of ?cc candidates in two
decay modes.
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Doubly Charmed Baryons
?cKp p 0 GeV/c
95 C.L.
?cKp p2.3 GeV/c
95 C.L.
?cKpp p 0 GeV/c
95 C.L.
?cKpp p2.3 GeV/c
95 C.L.
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Doubly Charmed Baryons
?c0p p 0 GeV/c
95 C.L.
?c0p p 2 GeV/c
95 C.L.
?c0pp p 0 GeV/c
95 C.L.
?c0pp p 2 GeV/c
95 C.L.
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DsJ(2317) and DsJ(2460)
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Charm-Strange Mesons

• DsJ(2317) and DsJ(2460) first observed by BABAR
  and CLEO in cc continuum events, and by Belle in
  B decays

• Both masses unexpectedly low below DK and DK
  threshold, respectively
• Only isospin-violating or electromagnetic decays
  kinematically allowed ? narrow widths
• Decay pattern and decay angular distributions
  consistent with interpretation as JP0 and
  JP1, respectively

CLEO 13.5 fb-1 PRD 68, 032002 (2003)
Belle 124M BB PRL 91, 262002 (2003)
BABAR 91 fb-1 PRL 90, 242001 (2003)
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Charm-Strange Mesons

• Assuming DsJ(2317) and DsJ(2460) are 0 and 1
  respectively, the decay channels below are
  allowed or forbidden as indicated.

• All of the above decay modes have been searched
  for.
• All Seen modes are also Allowed

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DsJ(2317)

• Original DsJ(2317) discovery mode update

• No indication of neutral or doubly-charged
  signal, ruling out some exotic interpretations

N318080
2 MeV/c2 Bins
Dsp
Circles Ds sidebands
Ds(2112) reflection
Dsp
Dark shade DsJ(2460) reflection
2317 MeV/c2
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DsJ(2460)

• DsJ(2460) decay channels
• Original Ds p0, Ds?Ds ?
• Additional Ds?
• Additional Dspp-

N56040
N92060
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DsJ(2460)

• Combining the three DsJ(2460) decay channels

• New branching ratios are well measured
• Limits are set for additional allowed/forbidden
  decay channels.

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DsJ(2460) Absolute Branching Fractions

• Sample with one B fully reconstructed (Breco)
• Study decays of other B?D(),0 X
• Observe DsJ(2460) signals in the recoil mass
  (mX)

hep-ex/0604030
(0.88 0.20 0.14)
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DsJ(2460) Absolute Branching Fractions

• Combine with previously measured product
  branching fractions

• Sum of known branching fractions 0.760.17

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X(3872) and Y(4260)
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X(3872)
Recently updated result from BABAR

• Initial discovery of B ? X(3872)K ? J/? pp
  K by Belle
• Confirmed by CDF and BABAR

PRD 73, 011101 (2006)
N498
N6115 (6.1 s)
hep-ex/0505038
B only
Solid Hist. mES sidebands
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X(3872)

• X(3872)???-J/? is an isospin-violating decay
• No charged partners found

PRD 71, 031501 (2005)

• New decay mode observed
• X(3872) ? ?J/?
• This implies that X(3872) is a C state

N196 (3.4 s)
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Y(4260)

• Searching for X(3872) in ISR events but found
  Y(4260)

Peak cross section s(ee-?Y)(5112) pb
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Y(4260)
CLEO results confirm Y(4260)
hep-ex/0602034

• Consistent with BABAR cross section
• No J/? p0 decay signal seen

N37 (11 s)
N8 (5.1 s)
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Y(4260)

• Searches for decays of Y(4260) to DD, fpp, and pp
  all do not find signal.

M(KK-)
PRD 73, 012005 (2006)
Y(4260)
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Summary
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Summary

• Charmed spectroscopy at BABAR is very active and
  pushing the boundaries of our knowledge.
• ?c(2940) A new charmed baryon above the Dp
  threshold.
• ?cc and ?cc are searched for but none seen by
  BABAR
• An update on newly discovered cs states that
  challenge theoretical predictions for mass
• X(3872) and Y(4260) discoveries and updates

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