Observation of the decay Bs0→D¯0ϕ

First observation of the decay Bs0→D¯0ϕ is reported using pp collision data, corresponding to an integrated luminosity of 1.0 fb−1, collected by the LHCb experiment at a centre-of-mass energy of 7TeV. The significance of the signal is 6.5 standard deviations. The branching fraction is measured relative to that of the decay Bs0→D¯0K¯⁎0 to beB(Bs0→D¯0ϕ)B(Bs0→D¯0K¯⁎0)=0.069±0.013(stat)±0.007(syst). The first measurement of the ratio of branching fractions for the decays Bs0→D¯0K¯⁎0 and B0→D¯0K⁎0 is found to beB(Bs0→D¯0K¯⁎0)B(B0→D¯0K⁎0)=7.8±0.7(stat)±0.3(syst)±0.6(fs/fd), where the last uncertainty is due to the ratio of the Bs0 and B0 fragmentation fractions.