Measurements of the branching fractions of $\hat{I}{ž}_c^0\to \hat{I}›K_S^0$, $\hat{I}{ž}_c^0\to \hat{I}{\pounds }^0{K}_S^0$, and $\hat{I}{ž}_c^0\to \hat{I}{\pounds }^{+}{K}^{-}$ decays at Belle

Abstract

Using the entire data sample of $980{\mathrm{fb}}^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider, we present measurements of the branching fractions of the Cabibbo-favored decays $\hat{I}{ž}_c^0\to \hat{I}›K_S^0$, $\hat{I}{ž}_c^0\to \hat{I}{\pounds }^0{K}_S^0$, and $\hat{I}{ž}_c^0\to \hat{I}{\pounds }^{+}{K}^{-}$. Taking the decay $Ξ_c^0 \to Ξ^- \pip$ as the normalization mode, we measure the branching fraction ratio $\mathcal{B}(\hat{I}{ž}_c^0\to \hat{I}›K_S^0)/\mathcal{B}(\hat{I}{ž}_c^0\to \hat{I}{ž}^{-}\ddot{I}{€}^{+})=0.229\pm 0.008\pm 0.012$ with improved precision, and measure the branching fraction ratios $\mathcal{B}(\hat{I}{ž}_c^0\to \hat{I}{\pounds }^0{K}_S^0)/\mathcal{B}(\hat{I}{ž}_c^0\to \hat{I}{ž}^{-}\ddot{I}{€}^{+})=0.038\pm 0.006\pm 0.004$ and $\mathcal{B}(\hat{I}{ž}_c^0\to \hat{I}{\pounds }^{+}{K}^{-})/\mathcal{B}(\hat{I}{ž}_c^0\to \hat{I}{ž}^{-}\ddot{I}{€}^{+})=0.123\pm 0.007\pm 0.010$ for the first time. Taking into account the branching fraction of the normalization mode, the absolute branching fractions are determined to be $\mathcal{B}(\hat{I}{ž}_c^0\to \hat{I}›K_S^0)=(3.27\pm 0.11\pm 0.17\pm 0.73)\times 10^{-3}$, $\mathcal{B}(\hat{I}{ž}_c^0\to \hat{I}{\pounds }^0{K}_S^0)=(0.54\pm 0.09\pm 0.06\pm 0.12)\times 10^{-3}$, and $\mathcal{B}(\hat{I}{ž}_c^0\to \hat{I}{\pounds }^{+}{K}^{-})=(1.76\pm 0.10\pm 0.14\pm 0.39)\times 10^{-3}$. The first and second uncertainties above are statistical and systematic, respectively, while the third ones arise from the uncertainty of the branching fraction of $\hat{I}{ž}_c^0\to \hat{I}{ž}^{-}\ddot{I}{€}^{+}$.

10 pages, 4 figures, 3 tables; accepted for publication as a Letter in Physical Review D