1. Possible Interpretations of DsJ(2632)
Shi-Lin Zhu
Peking University
QWG2004
October 14, 2004
Collaborators: Y.-B. Dai, C. Liu, Y.-R. Liu
Hep-ph/ (PRD in press)
Hep-ph/

2. Advances in Hadron Spectroscopy Since 20031
Advances in Hadron Spectroscopy Since 2003
BES: pp_bar near-threshold enhancement in J/Psigamma pp_bar decays, I=0 channel; p Lambda_bar threshold enhancement in J/Psi K p Lambda_bar
BABAR/CLEO/BELLE: narrow states DsJ(2317), DsJ(2457) below threshold
LEPS and others found evidence of Pentaquarks!
BELLE/CDFII: new narrow state X(3872)
E852: two exotic mesons with JPC=1-+ at 1709/2001MeV
SELEX: narrow state DsJ(2632) above threshold with abnormal decay pattern

3. SELEX observed DsJ(2632) in Ds+ eta and D0K+ modes
2+ state in (1+, 2+)
doublet in HQET
49.3 events
14 events
7.2 sigma
5.3 sigma

4. BABAR, CLEO, FOCUS didn’t see DsJ(2632)

5. Non-observation of a particular state in certain4
SELEX:
fixed-target hadroproduction
600 GeV Sigma- beam which consists strange quark explicitly
looks at very large Xf, not available for e+e- colliders
Production: gluon-gluon fusion
BABAR/CLEO:
e+e- colliders , center of mass close to Upsilon
Production: e+e- annihilation
FOCUS:
photoproduction
doesn't see double-charm hadrons but they exist!
Non-observation of a particular state in certain
experiments does not exclude its possible existence
The production ratios of different charm states could be quite
different between e+e- annihilation and gluon-gluon fusion
According to Evdokimov at SELEX: If DsJ(2632) really exists
 Special mechanism in hadroproduction at large Xf

6. Three Puzzles of DsJ(2632) If Not Artifact5
Three Puzzles of DsJ(2632) If Not Artifact
Narrow decay width. 274 MeV above D0K+ and 116 MeV above Ds eta threshold, decay width less than 17 MeV. Naive expectation around (100~200) MeV
Is DsJ(2632) a cs_bar state?
L=0: [Ds(1968), D*s (2112)]
L=1, lP=1/2+: [DsJ (2317), DsJ (2457)]
L=1, lP=3/2+: [DsJ (2536), DsJ (2573)]
Too low for L=2 assignment
Is it the first radial excitation of D*s (2112)? (K.-T. Chao)
Unusual decay pattern
SU(3)F symmetry + cs_bar assignment SELEX

7. DsJ(2632) As a Tetraquark Version I: (Liu, Zhu, Dai, Liu) 6 SU(3) C-G
0+ isoscalar member in 15 rep., the ratio of SU(3) C-G coefficients
naturally explains its anomalous decay pattern:
Quark content:
Mass:
Decay pattern:
SU(3) C-G
Decay Momentum

8. Weight Diagram of Heavy Tetraquark Multiplets7
Weight Diagram of Heavy Tetraquark Multiplets

9. Version II: (Chen, Li; Gupta)8
Version II: (Chen, Li; Gupta)
Quark content:  fluctuates into
Hence main decay mode is
D0K+ requires  , component, OZI suppressed

10. Version IV: (Maiani;Nicolescu)9
Version III: (Chao)
Tightly bound diquark configuration which has small mixing with ,
 narrow total width
Mixing between  unusual decay pattern
Version IV: (Maiani;Nicolescu)
Quark content:
D0K+ suppressed while important
Decay pattern:
Prediction:

11. Problems With Tetraquark Scheme10
Problems With Tetraquark Scheme
There should be many other tetraquark partners of DsJ(2632). Where are they?
Its narrow width may require that quarks inside DsJ(2632) form tightly bound clusters like diquarks. Otherwise tetraquarks fall apart easily.
The first three versions of tetraquarks predict the same production rates for D+K0, D0K+ final states. The fourth version predicts very large D+K0 mode.
But SELEX didn't find any signal in the D+K0 channel!

12. DsJ(2632) as Radial Excitation12
DsJ(2632) as Radial Excitation
First radial excitation of Ds(2112) with JP=1- (Chao; Barnes et al.;Bereven, Rupp)
The nodal structure of its radial wave function ensures the narrow total width
Different decay momentum in two channels leads to anomalous decay pattern
Dynamical calculation very desirable and missing
Future experimental search for: (Dai, Liu, Liu, Zhu)
its SU(3) flavor partners DJ0,+(2530)
its B-meson analogues BJ 0,+(5840), BsJ+(5940)
S-wave two pion decay modes

13. 13
Large Nc And DsJ(2632) As A Hybrid Meson: Version I (Dai, Liu, Liu, Zhu)
In the large Nc limit, the dominant decay mode is for the gluon to split into a color-octet
recombines with pair to form
The Nc order of this decay amplitude is
No abnormal decay pattern as observed in SELEX 
This assignment not preferred!

14. Version II: Hybrid Scheme (Dai, Liu, Liu, Zhu)14
Decay mode (b) into glueball is dominant, Nc0, forbidden by kinematics
The subleading mode (c) into becomes dominant; is mixture of and
 Ds eta dominant
D0K+ can occur via mode (a)
c s_bar is color-singlet, additional 1/Nc suppression from color mismatch, its Nc order
But its mass and decay width needs dynamical calculation!

15. Summary SELEX observed DsJ(2632) but BABAR, CLEO, FOCUS didn’t see it.15
Summary
SELEX observed DsJ(2632) but BABAR, CLEO, FOCUS didn’t see it.
It could be an artifact.
If it really exists, it could be
- Tetraquark
- Radial excitation
- Heavy hybrid meson
- …