Observation of D^{0}D^{0} Mixing Using the CDF II Detector
Full CDF Run II dataset: 9.6 fb^{1}
S. Behari^{1}, P. Karchin^{2}, P. Maestro^{3}, M. Mattson^{2}
^{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
D^{0} → K^{+} π^{}
to the Cabibbofavored decay
D^{0} → K^{} π^{+}.
The charge conjugate decays are included. A signal of 33 × 10^{3}
D^{*+} → π^{+} D^{0},
D^{0} → K^{+} π^{}
decays is obtained with
proper decay times between 0.75 and 10 mean D^{0} 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 ppbar
collisions at sqrt(s) = 1.96 TeV. Assuming CP conservation, we search for
D^{0}D^{0} mixing and measure the mixing parameters to be
R_{D} = (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 nomixing hypothesis is excluded with a probability
equivalent to 6.1 Gaussian standard deviations, providing an observation of
D^{0}D^{0} 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

Documentation
Supporting Plots
 D^{0} signal:
 D^{*+} signal:
 Secondary (B) contribution:
 [PNG,
EPS,
PDF] Impact parameter
(d_{0}) for RS D^{*+}
 [PNG,
EPS,
PDF] Secondary fraction
(f_{B}), the fraction of nonprompt RS D^{*+} decays
 Statistical interpretation:
 [PNG,
EPS,
PDF] A frequentist pvalue test
comparing χ^{2} difference between mixing and nomixing fits
 [PNG,
EPS,
PDF] Comparison of
(x'^{2},y') contours between experiments.
 Selection cuts:
 [PNG,
EPS,
PDF] Rightsign vs
Wrongsign Kπ mass before
signal selection
 [PNG,
EPS,
PDF] Rightsign vs
Wrongsign Kπ mass illustrating
the oppositemassassignment requirement for Wrongsign signal selection
 [PNG,
EPS,
PDF] Rightsign Kπ mass BEFORE signal selection
[PNG,
EPS,
PDF] Rightsign Kπ mass AFTER signal selection
 [PNG,
EPS,
PDF] Wrongsign Kπ mass BEFORE signal selection
[PNG,
EPS,
PDF] Wrongsign Kπ mass AFTER signal selection
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Last modified: 04/08/2013