Experimental Study Of Ψ(3770) AndΨ(2S)→Light Hadronic Final States Including φ

The research on non-DD decay of charmonium states above DD threshold is an important topic in τ-charm physics. Ψ(3770) is the first charmonium state above DD threshold, and the studies of its properties are still on going. In traditional quarkonium potential theory,Ψ(3770) decays dominantly to DD with the branching fraction more than98%. But this prediction has conflicts with the experiment measurements. Measurements of the total Ψ(3770) production cross section and the DD cross section indicate that Ψ(3770) may have larger branching fraction (about15%) to decay into non-DD final states. Charmless decays of the Ψ(3770) and Ψ(3686) can shed light on S-D mixing,"ρπ" puzzle, the discrepancy between the total and the DD cross section at the Ψ(3770), and rescattering effects in B meson decays.BES Ⅲ experiment has collected a big data sample on Ψ(3770) resonance (√(S)=3-773GeV) with integrated luminosity about2.917fb-1, which is the largest data sample in statistic in the world. Using this data sample and the continuum data taken at√s=3.65GeV, we have searched for some non-DD processes of Ψ(3770)→light hadrons including Φ. Ignoring the possible inter-ference between the Ψ(3770) decay and the e+e-QED production, we measured the branching fractions or the upper limits on the branching fractions of these decay modes, which areAmong these results, the measurements of B(Ψ(3770)→Φπ0π0) and B(Ψ(3770)→ΦKS0KS0) are done for the first time in experiment. Evidence for Ψ(3770)→ Φπ+π-with a significance of about3.1times standard deviation(σ)are found, corresponding to the upper limit of4.9×10-4at90％C.L..In this thesis,we have also measured the branching fraction of Ψ(3686)→Φπ+π-,Φπ0π0,ΦK+K-and ΦKS0+KS0,with the world’s largest Ψ(3686)data sam-ple.The results areAmong these results,the branching fraction of Ψ(3686)→Φπ0π0and Ψ(3686)→ΦKS0+KS0are measured for the first time in experiment.B(Ψ(3686)→Φπ+π-) and B(Ψ(3686)→ΦK+K-)agree with the PDG averaged value well.but with better precisions.The results in this thesis proyide important experimental information for the understanding of Ψ(3770)non-DD decays and "pπ" puzzle in Ψ(3686)decays.