Using ～14×106ψ(2S) and ～58×106J/ψ data collected at BESⅡ/BEPC,the branching fraction of ψ(2S) →Ω+Ωˉ+ is measured with about 5σ statistical significance.The Λ electric dipole and Λ decay parameter are studied using the decay J/ψ→ΛΛ→ ppˉπ+π-.Using(106±3)×106 ψ(2S) decays collected at BESⅢ/BEPCⅡ,we have obtained some interesting physics results.The branching fractions of χcJ →π0π0,ηη are measured with precision improved.The mass and width of hc(11P1) state,together with the branching fractions of Br(ψ(2S) →π0hc) and Br(hc →γηc) are the first measurements.Surprisingly,the decays of χc1 →φφ,ωω,and ωφ are firstly observed in BESⅢ data.
In reactor neutrino experiments, the analysis of time correlations between different physical events is an important task. Such analysis can help to understand the physical mechanisms of the signal and background events as well as the details of event selection and background estimation. This study investigates a "sampling and mixing" method used for producing large MC data samples for the Daya Bay reactor neutrino experiment. We designed a simple, generic mixing algorithm and generated large MC data samples for physics analysis from several samples according to their respective event rates. Basic plots based on the mixed data are shown.
We reported the observation of Y(2175) inφf_0(980)mass spectrum in J/ψ→ηφf_0(980)with fo(980)→π^+π^- and the observation of a broad 1^-- resonance of K^+ K^- mass in J/ψ→K^+ K^-π~0.The results from the partial wave analyses of J/ψ→γπ^+π^- andγπ~0π~0,as well as J/ψ→pK^-■are also presented.
The CP violation in the D system is predicted to be an unobserved level in the Standard Model. In this paper, we describe the method of searching for CP violation decay processes with the coherently produced D00 mesons from the ψ(3770) decay. The CP violation decay processes can be searched for at the BES-III experiment. The experimental sensitivity for searching for the CP violation can reach about a 10-4 level with a ψ(3770) data sample of about 20 fb-1.
