Measurements of CP asymmetries and branching fraction ratios of B− decays to two charm mesons

Searches for the rare hadronic decays B0→pp¯pp¯ and Bs0→pp¯pp¯ are performed using proton-proton collision data recorded by the LHCb experiment and corresponding to an integrated luminosity of 9  fb-1. Significances of 9.3σ and 4.0σ, including statistical and systematic uncertainties, are obtained for the B0→pp¯pp¯ and Bs0→pp¯pp¯ signals, respectively. The branching fractions are measured relative to the topologically similar normalization decays B0→J/ψ(→pp¯)K*0(→K+π-) and Bs0→J/ψ(→pp¯)⁢ϕ(→K+K-). The branching fractions are measured to be B(B0→pp¯pp¯)=(2.2±0.4±0.1±0.1)×10-8 and B(Bs0→pp¯pp¯)=(2.3±1.0±0.2±0.1)×10-8. In these measurements, the first uncertainty is statistical, the second is systematic, and the third one is due to the external branching fraction of the normalization channel.