Partial wave analysis of $J\mathrm{/}\psi \to \gamma {\eta }^{\mathrm{\prime }}{\eta }^{\mathrm{\prime }}$

Using a sample of $(10.09\pm 0.04)\times {10}^{9}J\mathrm{/}\psi$ events collected with the BESIII detector, a partial wave analysis of $J\mathrm{/}\psi \to \gamma {\eta }^{\mathrm{\prime }}{\eta }^{\mathrm{\prime }}$ is performed. The masses and widths of the observed resonances and their branching fractions are reported. The main contribution is from $J\mathrm{/}\psi \to \gamma f_0(2020)$ with $f_0(2020)\to {\eta }^{\mathrm{\prime }}{\eta }^{\mathrm{\prime }}$, which is found with a significance of greater than 25$\sigma$. The product branching fraction ${\cal B}\left(J/\psi\rightarrow\gamma f_0(2020)\right)\cdot{\cal B}\left(f_0(2020)\rightarrow\eta^{\prime}\eta^{\prime}\right)$ is measured to be $(2.63\pm 0.06(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{.}{)}_{-0.46}^{+0.31}(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{.}))\times {10}^{-4}$.