Measurement of the Charm Mixing Parameter $y_{CP}$ in Two-Body Charm Decays

We present a measurement of mixing in the $D^{0}-\bar{D}^0$ system through the parameter $y_{CP}$. This parameter is defined as the ratio of lifetimes measured in $D^0$ decays to the $CP$ eigenstate $K^{+}K^{-}$ with respect to decays to the Cabibbo favoured mode $K^{-}\pi^{+}$. The measurement is performed using absolute lifetime measurements exploiting a data-driven technique to correct for lifetime biasing effects. The result based on data collected in 2010 is \begin{align} y_{CP} = (5.5 \pm 6.3_{stat} \pm 4.1_{syst}) x 10^{-3}. \end{align}