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

Based on $7.33\text{}\text{}{\mathrm{fb}}^{-1}$ 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 ($1.2{4}_{-0.26}^{+0.28}\left(\mathrm{stat}\right)±0.06\left(\mathrm{syst}\right)\right)×{10}^{-4}$. 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 $1.7×{10}^{-4}$.