| Popis: |
Using 1310.6 × 106 J=ψ and 447.9 × 106 ψð3686Þ events collected with the BESIII detector at the BEPCII eþe− collider, the branching fractions and the angular distributions of J=ψ and ψð3686Þ decays to ΛΛ¯ and Σ0Σ¯ 0 final states are measured. The branching fractions are determined, with much improved precision, to be 19.43 0.03 0.33, 11.64 0.04 0.23, 3.97 0.02 0.12 and 2.44 0.03 0.11 for J=ψ → ΛΛ¯, J=ψ → Σ0Σ¯ 0, ψð3686Þ → ΛΛ¯ and ψð3686Þ → Σ0Σ¯ 0, respectively. The polar angular distributions of ψð3686Þ decays are measured for the first time, while those of J=ψ decays are measured with much improved precision. In addition, the ratios of branching fractions Bðψð3686Þ→ΛΛ¯Þ BðJ=ψ→ΛΛ¯Þ and Bðψð3686Þ→Σ0Σ¯ 0Þ BðJ=ψ→Σ0Σ¯ 0Þ are determined to test the “12% rule.” |
