Measurement of D⁰-D̅⁰ Mixing and CP Violation in Two-Body D⁰ Decays

We present a measurement of D⁰-D̅⁰ mixing and CP violation using the ratio of lifetimes simultaneously extracted from a sample of D⁰ mesons produced through the flavor-tagged process D*⁺ → D⁰π⁺, where D⁰ decays to K^∓ π^±, K⁻ K⁺, or π⁻ π⁺, along with the untagged decays D⁰ → K^∓ π^± and D⁰ → K⁻K⁺. The lifetimes of the CP-even, Cabibbo-suppressed modes K⁻K⁺ and π⁻ π⁺ are compared to that of the CP-mixed mode K^∓ π^± in order to measure y_{CP} and ΔY. We obtain y_{CP}=[0.72 ± 0.18(stat) ± 0.12(syst)]% and ΔY=[0.09 ± 0.26(stat) ±0.06(syst)]%, where ΔY constrains possible CP violation. The y_{CP} result excludes the null mixing hypothesis at 3.3σ significance. This analysis is based on an integrated luminosity of 468  fb⁻¹ collected with the BABAR detector at the PEP-II asymmetric-energy e⁺e⁻ collider.