PT Journal AU LHCb Collaboration (Aaij, Rea Garcia Martin, LM Henry, L Martinez-Vidal, F Oyanguren, A Remon Alepuz, C Ruiz Valls, P Ruiz Vidal, J Sanchez Mayordomo, C TI First observation of B+ -> D-s(+) K+ K- decays and a search for B+ -> D-s(+) phi decays SO Journal of High Energy Physics JI J. High Energy Phys. PY 2018 BP 131 EP 22pp VL 01 IS 1 DI 10.1007/JHEP01(2018)131https://arxiv.org/abs/1711.05637 LA English DE B physics; Branching fraction; Hadron-Hadron scattering (experiments); Rare decay AB A search for B+ -> D-s(+) K+ 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 13 TeV with the LHCb experiment. A significant signal is observed for the first time and the branching fraction is determined to be B(B+ -> D-s(+) K+ K-) = (7.1 +/- 0.5 +/- 0.6 +/- 0.7) x 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-s(+)(D) over bar (0). A search is also performed for the pure annihilation decay B+ -> D-s(+)(D) over bar (0). No significant signal is observed and a limit of B(B+ -> D-s(+) phi) < 4.9 x 10(-7) (4.2 x 10(-7)) is set on the branching fraction at 95% (90%) confidence level. ER