Search for CP violation in the decays $D^+_{(s)} \to K_S^0π^+$ and $D^+_{(s)} \to K_S^0K^+$

We have searched for CP violation in the charmed meson decays $D^{+}_{(s)}\to K^0_S\pi^+$ and $D^{+}_{(s)}\to K^0_S K^+$ using 673 fb$^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. No evidence for CP violation is observed. We report the most sensitive CP asymmetry measurements to date for these decays: $A_{CP}^{D^+\to K^0_S\pi^+}=(-0.71\pm0.19\pm0.20)%$, $A_{CP}^{D^+_s\to K^0_S\pi^+}=(+5.45\pm2.50\pm0.33)%$, $A_{CP}^{D^+\to K^0_S K^+}=(-0.16\pm0.58\pm0.25)%$, and $A_{CP}^{D^+_s\to K^0_S K^+}=(+0.12\pm0.36\pm0.22)%$, where the first uncertainties are statistical and the second are systematic.