Study of the Decays $D_s^{+}\to K_S^0{K}^{+}$ and $K_L^0{K}^{+}$

Abstract

Using an $e^{+}{e}^{-}$ annihilation data sample corresponding to an integrated luminosity of $3.19{\mathrm{fb}}^{-1}$ and collected at a center-of-mass energy $\sqrt{s}=4.178\mathrm{GeV}$ with the BESIII detector, we measure the absolute branching fractions $\mathcal{B}(D_s^{+}\to K_S^0{K}^{+})=(1.425\pm 0.038_{stat.}\pm 0.031_{syst.})\%$ and $\mathcal{B}(D_s^{+}\to K_L^0{K}^{+})=(1.485\pm 0.039_{stat.}\pm 0.046_{syst.})\%$. The branching fraction of $D_s^{+}\to K_S^0{K}^{+}$ is compatible with the world average and that of $D_s^{+}\to K_L^0{K}^{+}$ is measured for the first time. We present the first measurement of the $K_S^0$-$K_L^0$ asymmetry in the decays $D_s^{+}\to K_{S,L}^0{K}^{+}$, and $R(D_s^{+}\to K_{S,L}^0{K}^{+})=\frac{\mathcal{B}(D_s^{+}\to K_S^0{K}^{+})-\mathcal{B}(D_s^{+}\to K_L^0{K}^{+})}{\mathcal{B}(D_s^{+}\to K_S^0{K}^{+})+\mathcal{B}(D_s^{+}\to K_L^0{K}^{+})}=(-2.1\pm 1.9_{stat.}\pm 1.6_{syst.})\%$. In addition, we measure the direct $CP$ asymmetries $A_{\mathrm{CP}}(D_s^{\pm }\to K_S^0{K}^{\pm })=(0.6\pm 2.8_{stat.}\pm 0.6_{syst.})\%$ and $A_{\mathrm{CP}}(D_s^{\pm }\to K_L^0{K}^{\pm })=(-1.1\pm 2.6_{stat.}\pm 0.6_{syst.})\%$.