Study of $\eta (1475)$ and $X(1835)$ in radiative $J\mathrm{/}\psi$ decays to $\gamma \varphi$

The decay $J\mathrm{/}\psi \to \gamma \gamma \varphi$ is studied using a sample of $1.31\times {10}^9$ $J\mathrm{/}\psi$ events collected with the BESIII detector. Two structures around 1475 MeV/c${}^2$ and 1835 MeV/c${}^2$ are observed in the $\gamma \phi$invariantmassspectrumforthefirsttime\mathrm{.}Withafitonthe$\gamma \phi$ 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 $\eta (1475)$ 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 $13.5 \sigma$and$6.3 \sigma$,respectively\mathrm{.}Theresultsindicatethatboth$\eta(1475)$and$X(1835)$containasizeable$s\bar{s}$ component.