Observation of Bc+→J/ψDs+ and Bc+→J/ψDs*+ decays

The decays Bc+→J/ψDs+ and Bc+→J/ψDs*+ are observed for the first time using a dataset, corresponding to an integrated luminosity of 3 fb ^-1, collected by the LHCb experiment in proton-proton collisions at center-of-mass energies of √s=7 and 8 TeV. The statistical significance for both signals is in excess of 9 standard deviations. The following ratios of branching fractions are measured to be B(Bc+→J/ ψDs+)B(Bc+→J/ψπ ⁺)=2.90±0.57±0.24, B(Bc+→J/ψDs*+)B(Bc+→J/ψDs+)=2.37±0.56±0. 10, where the first uncertainties are statistical and the second systematic. The mass of the Bc+ meson is measured to be m _Bc+=6276.28±1. 44(stat)±0.36(syst) MeV/c2, using the Bc+→J/ψDs+ decay mode.