Measurement of $D^{+}\to K_S^0{K}^{+}$ and $D_s^{+}\to K_S^0{\pi }^{+}$ branching ratios

We report an improved measurement of $D^{+}\to K_S^0{K}^{+}$ and $D_s^{+}\to K_S^0{\pi }^{+}$ branching ratios using $605{\mathrm{fb}}^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The measured branching ratios with respect to the Cabibbo-favored modes are $\mathcal{B}(D^{+}\to K_S^0{K}^{+})/\mathcal{B}(D^{+}\to K_S^0{\pi }^{+})=0.1899\pm 0.0011\pm 0.0022$ and $\mathcal{B}(D_s^{+}\to K_S^0{\pi }^{+})/\mathcal{B}(D_s^{+}\to K_S^0{K}^{+})=0.0803\pm 0.0024\pm 0.0019$ where the first uncertainties are statistical and the second are systematic.

Figure 1

Invariant mass distribution of selected $K_S^0{K}^{+}$ pairs. Points with error bars show the data and histograms show the results of the fits described in the text. Signal, $D^{+}\to K_S^0{\pi }^{+}$ background, and random combinatorial background components are also shown.

Figure 2

Invariant mass distribution of selected $K_S^0{\pi }^{+}$ pairs. Points with error bars show the data and histograms show the results of the fits described in the text. Signal, $D_s^{+}\to K_S^0{K}^{+}$ background, and random combinatorial background components are also shown. The inset is an enlarged view of the $D_s^{+}$ region.