Updated determination of $D^0$-$\bar{D}{}^0$ mixing and CP violation parameters with $D^0\to K^{+}{\pi }^{-}$ decays

We report measurements of charm-mixing parameters based on the decay-time-dependent ratio of $D^0\to K^{+}{\pi }^{-}$ to $D^0\to K^{-}{\pi }^{+}$ rates. The analysis uses a data sample of proton-proton collisions corresponding to an integrated luminosity of $5.0$ fb${}^{-1}$ recorded by the LHCb experiment from 2011 through 2016. Assuming charge-parity (CP) symmetry, the mixing parameters are determined to be $x^{\mathrm{\prime }2}=(3.9\pm 2.7)\times {10}^{-5}$, $y’=(5.28 \pm 0.52) \times 10^{-3}$,and$R_D=(3.454 \pm 0.031)\times10^{-3}$. Without this assumption, the measurement is performed separately for $D^0$ and $\bar{D}{}^0$ mesons, yielding a direct CP-violating asymmetry $A_D =(-0.1\pm9.1)\times10^{-3}$,andmagnitudeoftheratioofmixingparameters$1.00< |q/p| <1.35$atthe$68.3%$ confidence level. All results include statistical and systematic uncertainties and improve significantly upon previous single-measurement determinations. No evidence for CP violation in charm mixing is observed.