A measurement of the ratios of the effective decay widths of $D^0\to {\pi }^{-}{\pi }^{+}$ and $D^0\to K^{-}{K}^{+}$ decays over that of $D^0\to K^{-}{\pi }^{+}$ decays is performed with the LHCb experiment using proton–proton collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of $6{\mathrm{fb}}^{-1}$. These observables give access to the charm mixing parameters $y_{CP}^{\pi \pi }-y_{CP}^{K\pi }$ and $y_{CP}^{KK}-y_{CP}^{K\pi }$, and are measured as $y_{CP}^{\pi \pi }-y_{CP}^{K\pi }=(6.57\pm 0.53\pm 0.16)\times {10}^{-3}$, $y_{CP}^{KK}-y_{CP}^{K\pi }=(7.08\pm 0.30\pm 0.14)\times {10}^{-3}$, where the first uncertainties are statistical and the second systematic. The combination of the two measurements is $y_{CP}-y_{CP}^{K\pi }=(6.96\pm 0.26\pm 0.13)\times {10}^{-3}$, which is four times more precise than the previous world average.

• Received 23 February 2022
• Accepted 6 May 2022

DOI:https://doi.org/10.1103/PhysRevD.105.092013

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

© 2022 CERN, for the LHCb Collaboration