First Observation of the Rare Purely Baryonic Decay B0→p¯p

Abstract

The first observation of the decay of a B0 meson to a purely baryonic final state, B0→p p ¯ , is reported. The proton-proton collision data sample used was collected with the LHCb experiment at center-of-mass energies of 7 and 8 TeV and corresponds to an integrated luminosity of 3.0 fb-1. The branching fraction is determined to be B (B0→p p ¯ )=(1.25 ±0.27 ±0.18 )×10-8 , where the first uncertainty is statistical and the second systematic. The decay mode B0→p p ¯ is the rarest decay of the B0 meson observed to date. The decay Bs0→p p ¯ is also investigated. No signal is seen and the upper limit B (Bs0→p p ¯ )<1.5 ×10-8 at 90% confidence level is set on the branching fraction.