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

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

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

J/ results Moriond QCD ,2007

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

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

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

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

Observation of  mass threshold enhancement in J/ background X(1810) M2(g) M2(gw) M() Spin-parity favors 0++ Phys. Rev. Lett., 96 (2006) 162002 Possible interpretations: Multiquark, Hybrid, Glueball Moriond QCD ,2007

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

(2S) results Moriond QCD ,2007

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

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

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

Multi-body ’ decays BESII, PRD73, 052004 (2006) Moriond QCD ,2007

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

(2S) radiative decay Many channels for (2S)+hadrons with the invariant mass of hadrons below 2.9GeV have been studied. Hep-ex/0612016 Moriond QCD ,2007

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 +3 +5 -10 -25 M=1859 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

(2S) radiative decay PRD74, 072001(2006) Moriond QCD ,2007

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

(2S)+ Bree Br Br/0.3885 7.350.18 7.3  0.8 7.93  0.54  0.97 PRD74, 112003(2006) Moriond QCD ,2007

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

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

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