Measurements of charm mixing parameters from the decaytimedependent ratio of D0>K+pi to D0>Kpi+ rates and the chargeconjugate ratio are reported. The analysis uses data, corresponding to 3 fb^{1} of integrated luminosity, from protonproton collisions at 7 and 8 TeV centerofmass energies recorded by the LHCb experiment. In the limit of chargeparity (CP) symmetry, the mixing parameters are determined to be x'^2=(5.5 + 4.9)x10^{5}, y'= (4.8 + 1.0)x10^{3}, and R_D=(3.568 + 0.066)x10^{3}. Allowing for CP violation, the mixing parameters are determined separately for D0 and D0bar mesons yielding A_D = (0.7 + 1.9), for the direct CPviolating asymmetry, and 0.75 < q/p< 1.24 at the 68.3 confidence level, where q and p are parameters that describe the mass eigenstates of the neutral charm mesons in terms of the flavor eigenstates. This is the most precise determination of these parameters from a single experiment and shows no evidence for CP violation.
Distribution of $ M( D ^0 \pi_{\rm s} ^+)$ for selected (a) rightsign $ D ^0 \rightarrow K^\pi^+$ and (b) wrongsign $ D ^0 \rightarrow K^+\pi^$ candidates. 
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Efficiencycorrected ratios of WStoRS yields for (a) $ D ^{*+}$ decays, (b) $ D ^{*}$ decays, and (c) their differences as functions of decay time in units of $ D ^0$ lifetime. Projections of fits allowing for (dashed line) no $ C P$ violation, (dotted line) no direct $ C P$ violation, and (solid line) full $ C P$ violation are overlaid. The abscissa of the data points corresponds to the average decay time over the bin; the error bars indicate the statistical uncertainties. 
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Twodimensional confidence regions in the $(x'^2,y')$ plane obtained (a) without any restriction on $ C P$ violation, (b) assuming no direct $ C P$ violation, and (c) assuming $ C P$ conservation. The dashed (solid) curves in (a) and (b) indicate the contours of the mixing parameters associated with $\overline{ D }{} ^0$ ( $ D ^0$ ) decays. The bestfit value for $\overline{ D }{} ^0$ ( $ D ^0$ ) decays is shown with an open (filled) point. The solid, dashed, and dotted curves in (c) indicate the contours of $ C P$ averaged mixing parameters at 68.3%, 95.5%, and 99.7% confidence level (CL), respectively. The bestfit value is shown with a point. 
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Animated gif made out of all figures. 
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Results of fits to the data for different hypotheses on the $ C P$ symmetry. The reported uncertainties are statistical and systematic, respectively; ndf indicates the number of degrees of freedom. See App. A for fits results including correlation coefficients. 
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Detailed fit results. Reported uncertainties and correlation coefficients include both statistical and systematic sources. 
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Created on 11 July 2020.