Observation of the doubly Cabibbo-Suppressed decays $D^{+}\to K^{+}{\pi }^0{\pi }^0$ and $D^{+}\to K^{+}{\pi }^0\eta$

Abstract

By analyzing $e^{+}{e}^{-}$ annihilation data corresponding to an integrated luminosity of $2.93\mathrm{f}{\mathrm{b}}^{-1}$ collected at the center-of-mass energy of 3.773\,GeV with the BESIII detector, we report the first observations of the doubly Cabibbo-suppressed decays $D^{+}\to K^{+}{\pi }^0{\pi }^0$ and $D^{+}\to K^{+}{\pi }^0\eta$. The branching fractions of $D^{+}\to K^{+}{\pi }^0{\pi }^0$ and $D^{+}\to K^{+}{\pi }^0\eta$ are measured to be $(2.1\pm 0.4_{\mathrm{stat}}\pm 0.1_{\mathrm{syst}})\times 10^{-4}$ and $(2.1\pm 0.5_{\mathrm{stat}}\pm 0.1_{\mathrm{syst}})\times 10^{-4}$ with statistical significances of 8.8$\sigma$ and 5.5$\sigma$, respectively. In addition, we search for the subprocesses $D^{+}\to K^{\ast }(892{)}^{+}{\pi }^0$ and $D^{+}\to K^{\ast }(892{)}^{+}\eta$ with $K^{\ast }(892{)}^{+}\to K^{+}{\pi }^0$. The branching fraction of $D^{+}\to K^{\ast }(892{)}^{+}\eta$ is determined to be $({4.4_{-1.5}^{+1.8}}_{\mathrm{stat}}\pm 0.2_{\mathrm{syst}})\times 10^{-4}$, with a statistical significance of 3.2$\sigma$. No significant signal for $D^{+}\to K^{\ast }(892{)}^{+}{\pi }^0$ is found and we set an upper limit on the branching fraction of this decay at the 90\% confidence level to be $5.4\times 10^{-4}$.

JHEP accepted for publication