Observation of the Lambda0_b -> J/psi Lambda phi decay in proton-proton collisions at sqrt(s) = 13 TeV

The observation of the Λ0b→J/ψΛϕ decay is reported using proton-proton collision data collected at √s=13TeV by the CMS experiment at the LHC in 2018, corresponding to an integrated luminosity of 60fb−1. The ratio of the branching fractions B(Λ0b→J/ψΛϕ)/B(Λ0b→ψ(2S)Λ) is measured to be (8.26±0.90(stat)±0.68(syst)±0.11(B))×10−2, where the first uncertainty is statistical, the second is systematic, and the last uncertainty reflects the uncertainties in the world-average branching fractions of ϕ and ψ(2S) decays to the reconstructed final states.