# Measurement of the Charm-Mixing Parameter ${y}_{CP}$

11 January 2019

Abstract: A measurement of the charm-mixing parameter ${y}_{CP}$ using ${D}^{0}\to {K}^{+}{K}^{-}$, ${D}^{0}\to {\pi }^{+}{\pi }^{-}$, and ${D}^{0}\to {K}^{-}{\pi }^{+}$ decays is reported. The ${D}^{0}$ mesons are required to originate from semimuonic decays of ${B}^{-}$ and ${\overline{B}}^{0}$ mesons. These decays are partially reconstructed in a data set of proton-proton collisions at center-of-mass energies of 7 and 8 TeV collected with the LHCb experiment and corresponding to an integrated luminosity of $3\text{}\text{}{\mathrm{fb}}^{-1}$. The ${y}_{CP}$ parameter is measured to be $\left(0.57±0.13\left(\mathrm{stat}\right)±0.09\left(\mathrm{syst}\right)\right)%$, in agreement with, and as precise as, the current world-average value.

Published in: Physical Review Letters 122 (2019)