First Observation of CP Violation in [bar over B][superscript 0] → D[(*) over CP]h[superscript 0] Decays by a Combined Time-Dependent Analysis of BABAR and Belle Data

Abstract

We report a measurement of the time-dependent CP asymmetry of [bar over B][superscript 0] → D[(*) over CP]h[superscript 0] decays, where the light neutral hadron h[superscript 0] is a π[superscript 0], η, or ω meson, and the neutral D meson is reconstructed in the CP eigenstates K[superscript +]K[superscript -], K[0 over S]π[superscript 0], or K[0 over S]ω. The measurement is performed combining the final data samples collected at the ϒ(4S) resonance by the BABAR and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain (471 ± 3) × 10[superscript 6] B[bar over B] pairs recorded by the BABAR detector and (772 ± 11) × 10[superscript 6] B[bar over B] pairs recorded by the Belle detector. We measure the CP asymmetry parameters -η[subscript f]S = +0.66 ± 0.10(stat) ± 0.06(syst) and C = -0.02 ± 0.07(stat) ± 0.03(syst). These results correspond to the first observation of CP violation in [bar over B][superscript 0] → D[(*) over CP]h[superscript 0] decays. The hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 5.4 standard deviations.