Study of η(1475) and X(1835) in radiative J/ψ decays to γΦ

The decay J/ψ → γγΦ is studied using a sample of 1.31×109 J/ events collected with the BESIII detector. Two structures around 1475 MeV/c ² and 1835 MeV/c ² are observed in the invariant mass spectrum for the first time. With a fit on the γΦ invariant mass, which takes into account the interference between the two structures, and a simple analysis of the angular distribution, the structure around 1475 MeV/c ² is found to favor an assignment as the (1475) and the mass and width for the structure around 1835 MeV/c ² are consistent with the X(1835). The statistical significances of the two structures are 13.5σ and 6.3σ, respectively. The results indicate that both (1475) and X(1835) contain a sizeable s¯s component.