Amplitude analysis and branching fraction measurement of the decay $D^0\to K_S^0{\pi }^0{\pi }^0$

An amplitude analysis of the decay $D^0\to K_S^0{\pi }^0{\pi }^0$ is performed to determine the relative magnitudes and phases of different intermediate processes. The analysis uses $e^{+}{e}^{-}$ collision data collected at the center-of-mass energy of 3.773 GeV by the BESIII detector corresponding to an integrated luminosity of 20.3 $\mathrm{f}{\mathrm{b}}^{-1}$. The absolute branching fraction of $D^0\to K_S^0{\pi }^0{\pi }^0$ is measured to be $(1.026\pm {0.008}_{\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{.}}\pm {0.009}_{\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{.}})\mathrm{\%}$. The dominant intermediate process is $D^0\to {\bar{K}}^{\ast }(892{)}^0(\to K_S^0{\pi }^0){\pi }^0$, with a branching fraction of $(4.22\pm {0.09}_{\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{.}}\pm {0.14}_{\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{.}})\times {10}^{-3}$.