Measurement of CP observables in B^± → D^(*)K^± and B^± → D^(*) π ^± decays using two-body D final states

Measurements of CP observables in B^± → D^(*)K^± and B^± → D^(*)π^± decays are presented, where D^(∗) indicates a neutral D or D^∗ meson that is an admixture of meson and anti-meson states. Decays of the D^(∗) meson to the Dπ⁰ and Dγ final states are partially reconstructed without inclusion of the neutral pion or photon. Decays of the D meson are reconstructed in the K^±π^∓, K⁺K⁻, and π⁺π⁻ final states. The analysis uses a sample of charged B mesons produced in proton-proton collisions and collected with the LHCb experiment, corresponding to integrated luminosities of 2.0, 1.0, and 5.7 fb⁻¹ taken at centre-of-mass energies of 7, 8, and 13 TeV, respectively. The measurements of partially reconstructed B^± → D^(*)K^± and B^± → D^(∗)π^± with D → K^∓π^± decays are the first of their kind, and a first observation of the B^± → (Dπ0)D∗π± decay is made with a significance of 6.1 standard deviations. All CP observables are measured with world-best precision, and in combination with other LHCb results will provide strong constraints on the CKM angle γ. [Figure not available: see fulltext.]