Search for Mixing-Induced CP Violation Using Partial Reconstruction of B̅⁰ → D*Χℓ^⁻ ν̅_ℓ and Kaon Tagging

We describe in detail a previously published measurement of CP violation in B⁰-B̅⁰ oscillations, based on an integrated luminosity of 425.7 fb⁻¹ collected by the BABAR experiment at the PEPII collider. We apply a novel technique to a sample of about 6 million B⁰ → D⁺ Χℓ⁻ ν̅(ℓ) decays selected with partial reconstruction of the D⁺ meson. The charged lepton identifies the flavor of one B meson at its decay time, the flavor of the other B is determined by kaon tagging. We determine a CP violating asymmetry A(CP) = (N(B⁰B⁰) - N(B̅⁰B̅⁰)) / (N(B⁰B⁰) + N(B̅⁰B̅⁰))= (0.06 ± 0.17(-0.32)(+0.38))% corresponding to Δ(CP) = 1 - |q/p| = (0.29 ± 0.84(-1.61)(+1.88)) x 10⁻³. This measurement is consistent and competitive with those obtained at the B factories with dilepton events.