The Study Of J / ψ �' γΛ(?) Decay At BESIII

The study of baryon is an important part for High-energy physics.The J/ψparticle has been found in 1947, and J/ψdecay regarded as a promising place to study excited baryon states.After upgraded the BES III collected about 225 milloion J/ψevents and 100 milloinψ(2S)events in 2009. It is the largest J/ψdata sample in the world which provides a unigue experimental condition for us to study charmonium deacays and seach for the new forms of hadrons.Based on 225M J/ψdata samples, we study on the J/ψ→γΛΛ,J/ψ→γηc(ηc→ΛΛ) and J/ψ→0Λ-c.c,the branching ratios of these channels have been presented. The measured branching ratios,including statistic error and systematic error as below.The decay of J/ψ→Σ0Λ+c.c are observed and measured, the signals ofΣ0 andΣ0 are very clear. The result of J/ψ→γηc(ηc→ΛΛ) is consistent with the value in PDG. The branching ratio of J/ψ→γΛΛcan not be measured in this paper, because there are many uncertainty background events in this channel,the background events which many be come from the decays of A* or S*.Because of the uncertainty background we can't be sure if there is an enhancement nearΛΛmass threshold in J/ψ→γΛΛ.