Measurement of the Branching Fraction of ${\mathrm{\Lambda }}_c^{+}\to p{K}_S^0{\pi }^0$ at Belle

We report a precise measurement of the ratio of branching fractions $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}_S^0{\pi }^0)\mathrm{/}\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}^{-}{\pi }^{+})$ using 980 fb${}^{-1}$ of $e^{+}{e}^{-}$ data from the Belle experiment. We obtain a value of $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}_S^0{\pi }^0)\mathrm{/}\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}^{-}{\pi }^{+})=0.339\pm 0.002\pm 0.009$, where the first and second uncertainties are statistical and systematic, respectively. This Belle result is consistent with the previous measurement from the CLEO experiment but has a fivefold improvement in precision. By combining our result with the world average $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}^{-}{\pi }^{+})$, we obtain the absolute branching fraction $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}_S^0{\pi }^0)=(2.12\pm 0.01\pm 0.05\pm 0.10)\mathrm{\%}$, where the uncertainties are statistical, systematic, and the uncertainty in the absolute branching fraction scale $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to p{K}^{-}{\pi }^{+})$, respectively. This measurement can shed light on hadronic decay mechanisms in charmed baryon decays.