| Summary: | We report on the observation of D0−D¯0${D^0} - {mathop Dlimits^ ^0}$ oscillations by measuring the time-dependent ratio of yields for the rare decay D0 → K+π− to the favored decay D0 → K−π+ at the Collider Detector at Fermilab (CDF). Using 9.6 fb−1 of integrated luminosity of √s = 1.96 TeV pp¯$par p$ collisions recorded in the full CDF Run II, the signals of 7.6×106 D0 → K−π+ and 33×103 D0 → K+π− decays are reconstructed in D*-tagged events, with proper decay times between 0.75 and 10 mean D0 lifetimes. We measure the mixing parameters x′2 = (0.08 ± 0.18) × 10−3, y′ = (4.3 ± 4.3) × 10−3, and RD = (3.51 ± 0.35) × 10−3. Our results are consistent with standard model expectations and similar results from proton-proton collisions and exclude the no-mixing hypothesis with a significance equivalent to 6.1 standard deviations.
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