Measurement of $D^0$-${\kern 0.2em\overline{\kern -0.2em D}}{}^0$ Mixing Using $D^0 \rightarrow K^+ \pi^- \pi^+ \pi^-$ Decays

We present preliminary results from a measurement of $D^0$- ${\kern 0.2em\overline{\kern -0.2em D}}{}^0$ mixing using the decays $D^0 \rightarrow K^+ \pi^- \pi^+ \pi^-$ in 480~fb${}^{-1} $ of data collected with the {\sl B{\scriptsize A}B{\scriptsize AR}} detector at the PEP-II $e^+e^-$ colliding-beam storage rings at SLAC. We report results for the mixing parameters ${x^ {\prime}}^2$, $y^{\prime}$, and the doubly Cabibbo-suppressed decay rate $R_D$. We present results with and without assuming CP conservation.