Study of the decay $D^{+}\to K^{\ast }(892{)}^{+}{K}_S^0$ in $D^{+}\to K^{+}{K}_S^0{\pi }^0$

Based on an $e^{+}{e}^{-}$ collision data sample corresponding to an integrated luminosity of 2.93 ${\mathrm{f}\mathrm{b}}^{-1}$ collected with the BESIII detector at $\sqrt{s}=3.773\mathrm{G}\mathrm{e}\mathrm{V}$, the first amplitude analysis of the singly Cabibbo-suppressed decay $D^{+}\to K^{+}{K}_S^0{\pi }^0$ is performed. From the amplitude analysis, the $K^{\ast }(892{)}^{+}{K}_S^0$ component is found to be dominant with a fraction of $(57.1\pm 2.6\pm 4.2)\mathrm{\%}$, where the first uncertainty is statistical and the second systematic. In combination with the absolute branching fraction $\mathcal{B}(D^{+}\to K^{+}{K}_S^0{\pi }^0)$ measured by BESIII, we obtain $$\mathcal{B}$(D^+\to K^*(892)^+ K_S^0)=(8.69\pm0.40\pm0.64\pm0.51)\times10^{-3}$, where the third uncertainty is due to the branching fraction $\mathcal{B}(D^{+}\to K^{+}{K}_S^0{\pi }^0)$. The precision of this result is significantly improved compared to the previous measurement.