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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. Outline. J/ results Wide resonance X(1580). Threshold enhancement in J/
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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 InteractionsLa Thuile, Italy,10 – 24, March
Outline • J/ results • Wide resonance X(1580). • Threshold enhancement in J/ • , invisible • (2S) results • Hadronic decay • Radiative decay • (2S)+ • cJ decay Moriond QCD ,2007
Data samples 28M J/ (2S) 14M 4M 6.42 pb-1 continuum data at Ecm=3.65 GeV for background study. 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 • mass threshold enhancementin In this talk, I will report two new structures Moriond QCD ,2007
Observation of X(1580)inJ/ K+K- 0 Background Moriond QCD ,2007 PRL97,142002(2006)
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
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
BESII: PRD71, 072006 (2005) ’ 3-body BESII: PRD74, 12004 (2006) Moriond QCD ,2007
Multi-body ’ decays BESII, PRD73, 052004 (2006) Moriond QCD ,2007
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 • No obvious strong mass threshold enhancement was observed in • A 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 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) According to the hadron helicity conservation, the angular distribution of J/,(2S)B8B8 satisfy: Moriond QCD ,2007
(2S)+ PRD74, 112003(2006) Moriond QCD ,2007
cJ decay Most channels are measured for the first time Moriond QCD ,2007
cJK+ K K+ K cJ++ ppbar cJ+K,+ Moriond QCD ,2007
Summary • A wide 1-- resonance X(1580) is observed in J/K+K0 . • 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