Study of D^{+} and D_{s}^{+} Decay Properties at Belle

We report the first observation of the doubly Cabibbo-suppressed decay, $D^{+}_{s} \to K^{+}K^{+}\pi^{-}$ and the significantly improved measurement of the doubly Cabibbo-suppressed decay, $D^{+} \to K^{+}\pi^{+}\pi^{-}$ using $\textrm{605 fb}^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The branching ratio with respect to its Cabibbo-favored counterpart are $\mathcal{B}(D^{+}_{s} \to K^{+}K^{+}\pi^{-})/\mathcal{B}(D^{+}_{s} \to K^{+}K^{-}\pi^{+}) = 0.229\pm0.028\pm0.012)$ and $\mathcal{B}(D^{+} \to K^{+}\pi^{+}\pi^{-})/\mathcal{B}(D^{+} \to K^{-}\pi^{+}\pi^{+}) = (0.569\pm0.018\pm0.014)$, where the first uncertainties are statistical and the second is systematic. We also report the improved measurement of $D^{+} \to K^{0}_{S}K^{+}$ and $D^{+}_{s} \to K^{0}_{S}\pi^{+}$ branching ratios using the same amount of data samples. The measured branching ratios with respect to the Cabibbo-favored modes are $\mathcal{B}(D^{+} \to K^{0}_{S}K^{+})/\mathcal{B}(D^{+} \to K^{0}_{S}\pi^{+}) = (0.1899\pm0.0011\pm0.0018)$ and $\mathcal{B}(D^{+}_{s} \to K^{0}_{S}\pi^{+})/\mathcal{B}(D^{+}_{s} \to K^{0}_{S}K^{+}) = (0.0803\pm0.0024\pm0.0012)$.