Observation of D0-D0 Mixing Using the CDF II Detector

Full CDF Run II dataset: 9.6 fb-1

S. Behari1, P. Karchin2, P. Maestro3, M. Mattson2

1 Fermilab,    2 Wayne State University,    3 University of Siena and INFN, Italy
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We measure the time dependence of the ratio of decay rates for the rare decay D0 → K+ π- to the Cabibbo-favored decay D0 → K- π+. The charge conjugate decays are included. A signal of 33 × 103 D*+ → π+ D0, D0 → K+ π- decays is obtained with proper decay times between 0.75 and 10 mean D0 lifetimes. The data sample was recorded with the CDF II detector at the Fermilab Tevatron and corresponds to an integrated luminosity of 9.6 fb-1 for p-pbar collisions at sqrt(s) = 1.96 TeV. Assuming CP conservation, we search for D0-D0 mixing and measure the mixing parameters to be

RD = (3.51 ± 0.35) 10-3, y' = (4.3 ± 4.3) 10-3, and x'2 = (0.08 ± 0.18) 10-3.

We report Bayesian probability contours in the x'2-y' plane and find that the no-mixing hypothesis is excluded with a probability equivalent to 6.1 Gaussian standard deviations, providing an observation of D0-D0 mixing from a single experiment.


D*+ WS/RS Ratio vs proper decay time

  EPS   PDF


Bayesian probability intervals in (x'2,y') space

  EPS   PDF


Mixing parameters result     EPS   PDF

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Last modified: 04/08/2013