Study of the doubly Cabibbo-suppressed decays $D_s^{+}\to K^{+}{K}^{+}{\pi }^{-}$ and $D_s^{+}\to K^{+}{K}^{+}{\pi }^{-}{\pi }^0$

Based on 7.33 fb${}^{-1}$ of $e^{+}{e}^{-}$ collision data collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, the experimental studies of the doubly Cabibbo-suppressed decays $D_s^{+}\to K^{+}{K}^{+}{\pi }^{-}$ and $D_s^{+}\to K^{+}{K}^{+}{\pi }^{-}{\pi }^0$ are reported. We determine the absolute branching fraction of $D_s^{+}\to K^{+}{K}^{+}{\pi }^{-}$ to be ($1.23_{-0.25}^{+0.28}(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t})\pm 0.06(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t})$) $\times {10}^{-4}$. No significant signal of $D_s^{+}\to K^{+}{K}^{+}{\pi }^{-}{\pi }^0$ is observed and the upper limit on its decay branching fraction at 90% confidence level is set to be $1.7\times {10}^{-4}$.