UC Irvine

Based on a sample of (225.3 ± 2.8) × 106 J/ψ events collected with the BESIII detector, the electromagnetic Dalitz decays of J/ψ → Pe+e- (P = η'/η/π∗0) are studied. By reconstructing the pseudoscalar mesons in various decay modes, the decays J/ψ → η' e+e-, J/ψ → η e+e-, and J/ψ → π0 e+e- are observed for the first time. The branching fractions are determined to be B(J/ψ → η' e+e-) = (5.81 ± 0.16 ± 0.31) × 10-5, B(J/ψ → η e+e-) = (1.16 ± 0.07 ± 0.06) × 10-5, and B(J/ψ → π0 e+e-) = (7.56 ± 1.32 ±0.50) × 10-7, where the first errors are statistical and the second ones systematic.