Evidence for the Decay B0 → J/ψ ω and Measurement of the Relative Branching Fractions of B0s Meson Decays to J/ψ η and J/ψ η′

First evidence of the B0 → J/ψ ω decay is found and the B0s → J/ψ η and B0s → J/ψ η′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb^−1 collected by the LHCb experiment in proton–proton collisions at a centre-of-mass energy of √s = 7 TeV. The branching fractions of these decays are measured relative to that of the B0 → J/ψ ρ0 decay: B(B0 → J/ψ ω)/B(B0 → J/ψ ρ0) = 0.89 ± 0.19(stat)_{−0.13}^{+0.07}(syst), B(B0s → J/ψ η)/B(B0 → J/ψ ρ0) = 14.0 ± 1.2(stat)_{−1.5}^{+1.1}(syst)_{−1.0}^{+1.1}(fd/fs), B(B0s → J/ψ η′)/B(B0 → J/ψ ρ0) = 12.7 ± 1.1(stat)_{−1.3}^{+0.5}(syst)_{−0.9}^{+1.0}(fd/fs) where the last uncertainty is due to the knowledge of fd/fs, the ratio of b-quark hadronization factors that accounts for the different production rate of B0 and B0s mesons. The ratio of the branching fractions of B0s → J/ψ η′ and B0s → J/ψ η decays is measured to be B(B0s → J/ψη′)/B(B0s → J/ψ η) = 0.90 ± 0.09(stat)_{−0.02}^{+0.06}(syst).