Recent results on J/ψ radiative decays at BESIII

By using a data sample of 1.3 billion J/ψ events collected with the BESIII detector and the partial wave analysis method, we have investigated the KS0KS0η, π0π0 and ϕϕ systems produced in J/ψ radiative decays to search for exotic hadron states. The X(1835)→KS0KS0η process is observed for the first time with a statistical significance greater than 12.9σ, where the KS0KS0 system is dominantly produced through the f0(980), and the spin parity of the X(1835) is determined to be 0−+. A piecewise function of Mπ0π0 that describes the scalar and tensor ππ amplitudes is extracted in the model-independent amplitude analysis of J/ψ → γπ0π0. In the J/ψ → γϕϕ process, the η(2225) is confirmed and two additional pseudoscalar states, η(2100) and X(2500), are observed. Three tensors f2(2010), f2(2300) and f2(2340) previously observed in π−p→ϕϕn are also observed with a large production rate of the f2(2340).