Observation of the decay $B_s^0\to K^{0}p\bar{p}$ and measurement of the $B_{(s)}^0\to K^{0}p\bar{p}$ branching fractions

A study of the charmless baryonic decays $B_{(s)}^0\to K^{0}p\bar{p}$ is presented, where $B_{(s)}^0$ denotes either a $B^0$ or a $B_s^0$ meson. The analysis is based on proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8, and $13\mathrm{T}\mathrm{e}\mathrm{v}$, corresponding to an integrated luminosity of $9{\mathrm{f}\mathrm{b}}^{-1}$. The decay $B_s^0\to K^{0}p\bar{p}$ is observed for the first time, with a measured branching fraction of $(9.14\pm 1.69\pm 0.90\pm 0.33\pm 0.20)\times {10}^{-7}$ and a significance of $5.6\sigma$. The uncertainties respectively account for statistical and systematic contributions, the precision of the branching fraction of the normalisation channel $B^0\to K^0{\pi }^{+}{\pi }^{-}$ and the fragmentation fraction ratio $f_s\mathrm{/}{f}_d$. The branching fraction determined for $B^0\to K^{0}p\bar{p}$ is $(2.82\pm 0.08\pm 0.12\pm 0.10)\times {10}^{-6}$, which is the most precise measurement to date.