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

The decay $J/\psi \to \gamma \gamma \varphi $ is studied using a sample of $1.31×{10}^{9}\text{}\text{}J/\psi $ events collected with the BESIII detector. Two structures around $1475\text{}\mathrm{MeV}/{c}^{2}$ and $1835\text{}\mathrm{MeV}/{c}^{2}$ are observed in the $\gamma \varphi $ invariant mass spectrum for the first time. With a fit on the $\gamma \varphi $ invariant mass, which takes into account the interference between the two structures, and a simple analysis of the angular distribution, the structure around $1475\text{}\mathrm{MeV}/{c}^{2}$ is found to favor an assignment as the $\eta \left(1475\right)$ and the mass and width for the structure around $1835\text{}\mathrm{MeV}/{c}^{2}$ are consistent with the $X\left(1835\right)$. The statistical significances of the two structures are $13.5\sigma $ and $6.3\sigma $, respectively. The results indicate that both $\eta \left(1475\right)$ and $X\left(1835\right)$ contain a sizeable $s\overline{s}$ component.