Аннотация:A search for B+→D+sK+K− decays is performed using pp collision data corresponding to an integrated luminosity of 4.8 fb−1, collected at centre-of-mass energies of 7, 8 and 13TeV with the LHCb experiment. A significant signal is observed for the first time and the branching fraction is determined to be
B(B+→D+sK+K−)=(7.1±0.5±0.6±0.7)×10−6,
where the first uncertainty is statistical, the second systematic and the third due to the uncertainty on the branching fraction of the normalisation mode B+→D+sD¯¯¯0. A search is also performed for the pure annihilation decay B+→D+sϕ. No significant signal is observed and a limit of
B(B+→D+sϕ)<4.9×10−7(4.2×10−7)
is set on the branching fraction at 95% (90%
) confidence level.