Studies of Charmonium at BESIII

Based on ψ(3686) decays of 106 million, the 1.31 billion J/psi events and a data sample of ψ(3770) with 2.9 fb−1 integrated luminosity, many analyses are performed. Exclusively baryonic decays of the ψ(3770), the radiative transition ψ(3770)→γηc(2S), the ψ(3770) transition to χcJ, isospin violation decay χc0,2→π0ηc, the C−parity violation decays J/ψ→γγ,γϕ are searched for, but no significant signals are observed, and upper limits are set for these decays. The decays of ψ(3770)→γχc1 and J/ψ→π0ϕ signals are observed. These measurements provide more information on the charmonium structure, and the isospin and C-parity violation in the charmonium decays.