Observation of the decay B0s → K0p ¯p and measurement of the B0(s) → K0p ¯p branching fractions

A study of the charmless baryonic decays B0(s) → K0p¯p is presented, where B0
(s) denotes either a B0 or a B0s 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 TeV, corresponding to an integrated luminosity of 9 fb−1. The decay B0
s → K0p¯p is observed for the first time, with a measured branching fraction of (9.14±1.69±0.90±0.33±0.20)×10−7 and a significance of 5.6σ. The uncertainties respectively account for statistical and systematic contributions, the precision of the branching fraction of the normalisation channel B0 → K0π+π− and the
fragmentation fraction ratio fs/fd. The branching fraction determined for B0 → K0p¯p is (2.82 ± 0.08 ± 0.12 ± 0.10) × 10−6, which is the most precise measurement to date.