Abstract
We measure the rate of D-0-(D) over bar0 mixing with the observable y(CP) = (tau(K pi)/tau(KK)) - 1, where tau(KK) and tau(K pi) are, respectively, the mean lifetimes of CP-even D-0 -> K+K- and CP-mixed D-0 -> K-pi(+) decays, using a data sample of 384 fb(-1) collected by the BABAR detector at the SLAC PEP-II asymmetric-energy B Factory. From a sample of D-0 and (D) over bar0 decays where the initial flavor of the decaying meson is not determined, we obtain y(CP) = [1.12 +/- 0.26(stat) +/- 0.22(syst)]%, which excludes the no-mixing hypothesis at 3.3 sigma, including both statistical and systematic uncertainties. This result is in good agreement with a previous BABAR measurement of y(CP) obtained from a sample of D*(+) -> D-0 pi(+) events, where the D-0 rho decays to K-pi(+), K+K-, and pi(+)pi(-), which is disjoint with the untagged D-0 events used here. Combining the two results taking into account statistical and systematic uncertainties, where the systematic uncertainties are assumed to be 100% correlated, we find y(CP) = [1.16 +/- 0.22(stat) +/- 0.18(syst)]%, which excludes the no-mixing hypothesis at 4.1 sigma.
We are grateful for the extraordinary contributions of our
PEP-II colleagues in achieving the excellent luminosity and
machine conditions that have made this work possible. The
success of this project also relies critically on the expertise and
dedication of the computing organizations that supportBABAR.
The collaborating institutions wish to thank SLAC for its support
and the kind hospitality extended to them. This work
is supported by the US Department of Energy and National
Science Foundation, the Natural Sciences and Engineering
Research Council (Canada), the Commissariat à l'Energie
Atomique and Institut National de Physique Nucléaire et
de Physique des Particules (France), the Bundesministerium
für Bildung und Forschung and Deutsche Forschungsgemeinschaft
(Germany), the Istituto Nazionale di Fisica Nucleare
(Italy), the Foundation for Fundamental Research on Matter
(The Netherlands), the Research Council of Norway, the
Ministry of Education and Science of the Russian Federation,
Ministerio de Educación y Ciencia (Spain), and the Science
and Technology Facilities Council (United Kingdom). Individuals
have received support from the Marie-Curie IEF program
(European Union) and the A. P. Sloan Foundation.
Peer reviewed