Measurement of the B_s⁰ → ϕϕ branching fraction and search for the decay B⁰ → ϕϕ

Using a dataset corresponding to an integrated luminosity of 3.0 fb−1 collected in pp collisions at centre-of-mass energies of 7 and 8 TeV, the Bs0 → ϕϕ branching fraction is measured to be (formula presented.)where fs/fd represents the ratio of the Bs0to B0 production cross-sections, and the B0 → ϕK*(892)0 decay mode is used for normalization. This is the most precise measurement of this branching fraction to date, representing a factor five reduction in the statistical uncertainty compared with the previous best measurement. A search for the decay B0 → ϕϕ is also made. No signal is observed, and an upper limit on the branching fraction is set as B(B0 → φφ) < 2.8 × 10−8 at 90% confidence level. This is a factor of seven improvement compared to the previous best limit.