Observation of 𝐵⁺_𝑐 →𝐷⁢ℎ⁺⁡ℎ⁻ Decays

Searches are presented for 𝐵⁺_𝑐 →𝐷⁢ℎ^+⁡ℎ⁻ decays, where 𝐷 is a charmed meson and ℎ^± is a charged pion or kaon, using 𝑝⁢𝑝 collision data collected by the LHCb experiment corresponding to an integrated luminosity of 9  fb⁻¹. The decays 𝐵⁺_𝑐 →𝐷⁺⁢𝐾⁺⁢𝜋⁻, 𝐵⁺_𝑐 →𝐷^*+⁢𝐾⁺⁢𝜋⁻, and 𝐵⁺_𝑐 →𝐷⁺_𝑠⁢𝐾⁺⁢𝐾⁻ are observed for the first time. Their branching fractions, expressed as ratios relative to that of the 𝐵⁺_𝑐 →𝐵⁰_𝑠⁢𝜋⁺ decay, are determined to be 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, 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.