Recent measurements of charmonium decays at BESIII.

In this poster, we present the first measurement of the charmonium decay ψ (3686) → ϕKS0KS0, based on an analysis of a data set comprising (448.1 ± 2.9) × 106 ψ(3686) events collected by the BESIII detector operating at the BEPCII collider. Taking the interference between ψ(3686) decay and continuum production into account, clear signals of ψ (3686) → ϕKS0KS0 is observed and the branching fraction of ψ (3686) → ϕKS0KS0 is reported for the first time. Combined with the world average value for B (J / ψ → ϕKS0KS0, the 12% rule for this channel is tested with high precision. [ABSTRACT FROM AUTHOR]