1. New States Containing Charm at BABAR
PHENO 06 Symposium
A.J. Edwards - Stanford University
May 15

2. Outline Λc(2880)+ and Λc(2940)+ → D0p Ξcc+ and Ξcc++
New measurements of the Λc(2880)+
First observation of the Λc(2940)+
Ξcc+ and Ξcc++
Are double-charm baryons among us?
D*sJ(2317)+ and DsJ(2458)+
An update on their properties; absolute BFs for DsJ(2458)+
X(3872) and Y(4260)
Update & confirmation of X(3872) C-parity
Searches for new Y(4260) decay modes 2

3. Λc(2940)+ 3

4. Charm Baryon Spectroscopy
Two new observations in cc continuum of particles with decays to D0p
Discovery of Λc(2940)+
The first observation of Λc(2880)+ → D0p
Λc(2880)+
D0p Threshold π 4

5. A New Decay Mode, Mass and width
hep-ex/
(sub. to PRL) fb–1,
A New State
Λc(2880)+
N=2280±310
(>7 σ)
Λc(2940)+
M = (2939.8±1.3±1.0) MeV/c2
Γ = (17.5±5.2±5.9) MeV
Λc(2940)+
A New Decay Mode, Mass and width
Λc(2880)+
M = (2881.9±0.1±0.5) MeV/c2
Γ = (5.8±1.5±1.1) MeV
Wrong sign D0p
PDG04: M=2880.9±2.3 MeV/c2
Γ < 8 MeV
D0 mass sidebands 5

6. Λc(2940)+
Sascha Migura et al.
hep-ph/
hep-ex/
Three Λc states predicted at mass ~2940 MeV/c2: JP= (1/2)+, (1/2)–, and (3/2)–
The Λc(2880)+ is near a predicted (3/2)– state.
Λc(2940)+ not observed in Λc+π+π–. Suppression not understood.
Expected signal size
Neither signal in D+p distribution → both states are Λc’s 6

7. Doubly Charmed Baryons7

8. Doubly Charmed Baryons
SU(4) 20'-plet
Theoretically Ξcc & Ωcc should exist.
The SELEX experiment (hyperon beam) reports Ξcc evidence (with 1,630 Λc)
The FOCUS experiment (photon beam) sees no Ξcc evidence (with 19,500 Λc)
Strangeness
Charm I3
Can they be found in e+e– → qq production?
Ξc0→Ξ–π+
232 fb–1
Large numbers of single charm baryons in 232 fb–1 data set
e.g. ~600,000 Λc+ and ~12,000 Ξc0
Double charm baryon e+e– cross section predictions: fb
Theoretical BFs to Λc+K-π+, Λc+K-π+π+, Ξc0π+, Ξc0π+π+ ~ a few percent
Λc+→pK–π+
232 fb–1 8

9. Doubly Charmed Baryons
SELEX Ξcc+
Λc+→pK–π+
232 fb–1
Λc+K–π+
p*>2.3 GeV/c
Λc Sidebands
95% C.L.
SELEX Ξcc++
Λc+K–π+π– p*>2.3 GeV/c
<
95% C.L.
With some assumptions about branching fractions:
< % C.L. (p* > 2.3 GeV/c)
< % C.L. (p* > 2.3 GeV/c)
This does not rule out any theoretical production cross sections. 9

10. Doubly Charmed Baryons
SELEX Ξcc+
Ξc0π+
p*> 2 GeV/c
< 1.3 fb
95% C.L.
SELEX Ξcc++
< 3.4 fb
95% C.L.
Ξc0π+π+
p*> 2 GeV/c
Ξc0→Ξ–π+
232 fb–1
With some assumptions about branching fractions: The production cross section limits for doubly charmed baryons are near or below σ(e+e– → Ξc0X) 10

11. DsJ*(2317) and DsJ(2460) 11

12. 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 D*K threshold, respectively
Only isospin-violating or electromagnetic decays kinematically allowed  narrow widths
Decay pattern and decay angular distributions consistent with interpretation as JP=0+ and JP=1+, respectively
D*K
D0K
BABAR: 91 fb-1
PRL 90, (2003)
CLEO: 13.5 fb-1
PRD 68, (2003)
Belle: 124M BB
PRL 91, (2003) 12

13. Charm-Strange Mesons
Assuming DsJ*(2317) and DsJ(2460) have JP = 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” 13

14. D*sJ(2317)+ Original D*sJ(2317) discovery mode update
232 fb-1
sub. to PRD
No indication of neutral or doubly-charged signal, ruling out some exotic interpretations
N=3180±80
2 MeV/c2 Bins
Ds+π–
Circles: Ds sidebands
Ds*(2112)
reflection
Ds+π+
Dark shade:
DsJ(2460) reflection
2317 MeV/c2 14

15. Open points: Ds sidebands
DsJ(2460)+
DsJ(2460) decay channels
Original: Ds* π0, Ds*→Ds+ 
Additional: Ds+
Additional: Ds+π+π-
DsJ(2460)+Ds+π0
Dark shade:
DsJ*(2317)+
reflection
Open points: Ds sidebands
Light shade:
Ds*(2112)+
N=560±40
232 fb-1
sub. to PRD
DsJ(2460) → Ds+π+π-
DsJ*(2317)
N=123±15
N=6±3
DsJ(2460)+Ds+ 
Backgrounds
N=920±60 15

16. DsJ(2460)+ From the Ds+π+π– decay channel More precise BR measurements
Limits set for additional decay channels. 16

17. DsJ(2460)+ Absolute Branching Fractions
Sample with one B fully reconstructed (Breco)
Study decays of other B  (D*+, D+, D*0, D0) X
Observe DsJ(2460)- signals in the recoil mass (mX)
hep-ex/ e- D* p e+
Breco
Bsignal
D*0
D*+ D0 D+ X
BF( )
= (0.88 ± 0.20 ± 0.14) % 17

18. DsJ(2460)+ Absolute Branching Fractions
Combine with previously measured product branching fractions
230M BB and Using B(Ds→φπ)=4.62 %
Sum of known branching fractions: 0.76±0.17 18

19. X(3872) and Y(4260) 19

20. Updated result from BABAR
X(3872) → J/ψ π+ π–
Updated result from BABAR
Initial discovery of B– → X(3872)K– → J/ψ π+π– K– by Belle
Confirmed by CDF, DØ and BABAR
PRD 73, (2006), 232M BB
hep-ex/
N=49±8
N=61±15
(6.1 σ)
Updated 256 fb-1
Solid Hist.: mES sidebands 20

21. X(3872) → J/ψ γ BABAR confirms X(3872) → γJ/ψ
287M BB
N=19±6 (3.4 σ)
BABAR confirms X(3872) → γJ/ψ
This implies that X(3872) is a C=+1 state
All evidence points towards X(3872) being an isoscalar 1++ state 21

22. Y(4260) → J/ψ π+ π–
Searching for X(3872) in ISR events but found Y(4260)
→ JPC = 1– –
233 fb-1, PRL 95, (2005)
(2S)
Peak cross section:
σ(e+e-Y)=(51±12) pb 22

23. CLEO results confirm Y(4260)
Y(4260) → J/ψ π π
CLEO results confirm Y(4260)
hep-ex/
Consistent with BABAR cross section
No J/ψ π0 decay signal seen
N=37
N=8 23

24. Y(4260) Searches in ISR Processes
e+e– → γISR pp, (232 fb–1)
PRD 73, (2006)
e+e–→γISR DD (289 fb-1)
To.b.subm.to PRL
e+e–→γISRΦπ+π– (232 fb-1)
To.b.subm.to PRD
Y(4260)
M(K+K-)
ψ(3770)
γISR detected
γISR detection not required
γISR detected 24

25. Summary 25

26. Summary
Charm spectroscopy at BABAR is very active and pushing the boundaries of experimental knowledge.
Λc(2940)+ first observation; absence in D+p is consistent with Λc interpretation.
Λc(2880)+: first observation in D0p decay mode; improved (M,Γ); absence in D+p is consistent with Λc interpretation.
Ξcc+ and Ξcc++ are searched for but not found; limits not theoretically restrictive.
Updates on DsJ*(2317)+ and DsJ(2460)+; absolute branching fraction measurements for DsJ(2460)+
X(3872) update and confirmation of positive C parity from J/ψγ mode
Y(4260): limits on DD, φπ+π–, and pp decay modes 26