Search for Mixing and Charge Parity Violation in Neutral Charm Mesons through Semileptonic $B$ Meson Decay

We present the measurement of mixing and Charge Parity violation parameters in the $D^0$ meson system using the decay \begin{align} \overline{B}\to \mu^- D^{*+} X\\ D^{*+}\to D^0 \pi^+\\ D^0\to K \pi \end{align} and charge conjugate decays using the full Run I dataset collected by the LHCb Collaboration at the LHC at CERN from 2011 to 2012. By fitting the time dependent ratio of ``Wrong Sign'' $D^0$ decays to ``Right Sign'' $D^0$ decays, we extract the parameters sensitive to mixing and charge parity violation. The resulting mixing fit yields \begin{align} R_D &= (3.48 \pm 0.11 \pm 0.01)\times10^{-3}\\ y' &= (4.60 \pm 3.50 \pm 0.18)\times 10^{-3}\\ x'^2&= (0.28 \pm 3.10 \pm 0.11)\times 10^{-4}. \end{align} The results for the no Direct CP Violation fits are \begin{align} R_D &= (3.48 \pm 0.11 \pm 0.01)\times 10^{-3}\\ y'^+ &= (2.79 \pm 3.99 \pm 1.17)\times 10^{-3}\\ x'^{2+}&= (1.94 \pm 3.47 \pm 0.98)\times 10^{-4}\\ y'^- &= (6.51 \pm 4.17 \pm 1.66)\times 10^{-3}\\ x'^{2-}&= (-1.53 \pm 4.26 \pm 1.68)\times 10^{-4}. \end{align} The results for the All CP Violation allowed fit are \begin{align} R_D^+ &= (3.38 \pm 0.15 \pm 0.06)\times 10^{-3}\\ y'^+ &= (5.81 \pm 5.02 \pm 0.32)\times 10^{-3}\\ x'^{2+}&= (-0.19 \pm 4.44 \pm 0.31)\times 10^{-4}\\ R_D^- &= (3.60 \pm 0.15 \pm 0.07)\times 10^{-3}\\ y'^- &= (3.32 \pm 4.87 \pm 0.40)\times 10^{-3}\\ x'^{2-}&= (0.79 \pm 4.33 \pm 0.38)\times 10^{-4}. \end{align} The results are consistent with $CP$ symmetry. We provide the LHCb average of WS searches, and predictions of the world averages of the underlying physics parameters with the inclusion of this result.