Observation of Bc⁺ → D h⁺ h⁻ decays

Searches are presented for Bc⁺ → D h⁺ h⁻ decays, where D is a charmed meson and h± is a charged pion or kaon, using $pp$ collision data collected by the LHCb experiment corresponding to an integrated luminosity of 9~fb⁻¹. The decays Bc⁺→ D⁺ K⁺π⁻, Bc⁺→ D*+ K⁺π⁻ and Bc⁺→ Dₛ⁺ K⁺ K⁻ are observed for the first time. Their branching fractions, expressed as ratios relative to that of the Bc⁺→ Bₛ⁰π⁺ decay, are determined to be {align*} R(B_c^+→ D^+ K^+π^-) =(1.96 ± 0.23± 0.08 ± 0.10)× 10⁻³,&\\ R(B_c^+→ D*+ K^+π^-) =(3.67 ± 0.55 ± 0.24± 0.20)× 10⁻³,&\\ R(B_c^+→ D_s^+ K^+ K^-) =(1.61 ± 0.35± 0.13± 0.07)× 10⁻³, {align*} where the first uncertainty is statistical, the second is systematic, and the third is due to the limited precision on the D-meson branching fractions. The decay channels proceed primarily through excited K⁰ or D⁰ resonances or $ϕ$ mesons, and open a new avenue for studies of charge-parity violation in beauty mesons.