1. Recent Results of J/ and (2S) at BESII
Zhiyong Wang
IHEP, Beijing
for the BES Collaboration
Rencontres de Moriond 2007
QCD and High Energy Hadronic Interactions La Thuile, Italy, 10 – 24, March
Moriond QCD, 2007

2. Outline J/ results (2S) results Wide resonance X(1580).
Threshold enhancement in J/
,  invisible
(2S) results
Hadronic decay
Radiative decay
(2S)+
cJ decay
Moriond QCD ,2007

3. Ecm=3.65 GeV for background study.
Data samples
28M
J/
(2S)
14M 4M
6.42 pb-1 continuum data at
Ecm=3.65 GeV for background study.
Moriond QCD ,2007
Moriond QCD, 2007

4. J/ results
Moriond QCD ,2007

5. New Observations at BESII
In past three years, a number of new structures were observed at BESII
A possible bound state: mass threshold enhancement in and new observation of X(1835) in
mass threshold enhancement in
In this talk, I will report two new structures 
Moriond QCD ,2007
Moriond QCD, 2007

6. Observation of X(1580) in J/  K+K- 0
Background
Moriond QCD ,2007
PRL97,142002(2006)
Moriond QCD, 2007

7. How to understand broad X(1580)?
Search of a similar structure in J/  KSK  will help to determine its isospin.
X(1580) could have different nature from conventional mesons:
Width is much broader than other mesons.
Broad width is expected for a multiquark state.
Moriond QCD ,2007

8. Observation of  mass threshold enhancement in J/
We studied DOZI process:
J/    +  
 
+-0 K+ K-   
recoiling against 
Moriond QCD ,2007
Moriond QCD, 2007

9. Observation of  mass threshold enhancement in J/
background
X(1810)
M2(g)
M2(gw)
M()
Spin-parity favors 0++
Phys. Rev. Lett., 96 (2006)
Possible interpretations: Multiquark, Hybrid, Glueball
Moriond QCD ,2007

10. Searching for /’ Invisible Decays Via J//’
Reconstructing K+K ,
looking at missing momentum of  decays
Fast  (1.2 GeV) will help us define the decay
direction of invisible decay of / (958) .
Missing
direction
Tag direction
No any hit information are required
outside of the core of  decays.
Signal MC
58 M J/
 missing momentum distribution
PRL97,202002(2006)
Moriond QCD ,2007

11. (2S) results
Moriond QCD ,2007

12. (2S) hadronic decay
M. Appelquist and H. D. Politzer, PRL34, 43 (1975)
Moriond QCD ,2007

13. ’ 3-body PRD71,072006(2005); PRD74, 12004 (2006) 256±18 44.8±8.7
914±42
921±40
Moriond QCD ,2007

14. ’ 3-body BESII: PRD71, 072006 (2005) BESII: PRD74, 12004 (2006)
Moriond QCD ,2007

15. Multi-body ’ decays
BESII, PRD73, (2006)
Moriond QCD ,2007

16. Many intermediate states are observed for the first time.
Multi-body ’ decays
Many intermediate states are observed for the first time.
Moriond QCD ,2007

17. (2S) radiative decay
Many channels for (2S)+hadrons with the invariant mass of hadrons below 2.9GeV have been studied.
Hep-ex/
Moriond QCD ,2007

18. Search for the strong mass threshold enhancement X(1860) in
A strong mass threshold enhancement was observed in
No obvious strong mass threshold enhancement was observed in
M= MeV/c2
G < 30 MeV/c2 (90% CL)
acceptance
Fit
acceptance
0.1
0.2
0.3
X(1860)
M(pp)-2mp (GeV)
Moriond QCD ,2007

19. (2S) radiative decay
PRD74, (2006)
Moriond QCD ,2007

20. Accepted by PLB B(BBbar) Channel CLEOc BES-II Theo. Exp.
2.870.120.15
3.310.090.23
3.280.230.25
3.390.200.32
2.630.350.21
2.350.360.32
2.380.300.21
3.000.420.31
According to the hadron helicity conservation, the angular distribution of J/，(2S)B8B8 satisfy:
Theo.
Exp.
0.58
Claudson et al
0.670.150.04
E835
0.80
Carimalo
0.850.240.04
BES
Moriond QCD ,2007

21. (2S)+ Bree Br Br/0.3885 7.350.18 7.3  0.8
7.93  0.54  0.97
PRD74, (2006)
Moriond QCD ,2007

22. cJ decay Most channels are measured for the first time
PLB642,197(2006)
PRD73,052006(2006)
PRD74,072001(2006)
Most channels are measured for the first time
Moriond QCD ,2007

23. cJK+ K K+ K cJ++ ppbar cJ+K,+
Moriond QCD ,2007

24. Summary
A wide 1-- resonance X(1580) is observed in J/K+K0 .
The mass threshold enhancement is observed in J/.
The invisible decay mode is studied for  and  via J//.
A lot of (2S) radiative and hadronic decay channels are measured and the 12% rule are tested.
Many cJ decay modes are observed and most are measured for the first time.
Thanks a lot !
Moriond QCD ,2007