Search for the rare hadronic decay Bs0→pp¯

A search for the rare hadronic decay B0 s → pp¯ is performed using proton-proton collision data recorded by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb−1. No evidence of the decay is found and an upper limit on its branching fraction is set at BðB0 s → pp¯Þ < 4.4ð5.1Þ × 10−9 at 90% (95%) confidence level; this is currently the world’s best upper limit. The decay mode B0 → pp¯ is measured with very large significance, confirming the first observation by the LHCb experiment in 2017. The branching fraction is determined to be BðB0 → pp¯Þ¼ð1.27 0.15 0.05 0.04Þ × 10−8, where the first uncertainty is statistical, the second is systematic and the third is due to the external branching fraction of the normalization channel B0 → Kþπ−. The combination of the two LHCb measurements of the B0 → pp¯ branching fraction yields BðB0 → pp¯Þ¼ð1.27 0.13 0.05 0.03Þ × 10−8.