Branching ratio and decay asymmetry measurement of $B^- \to D^0 K^-$ with $D^0 \to \pi \pi \pi^0$

We report on the observation of the decay $B^0\to D^0/\bar{D^0} K^-$ with $D^0/\bar{D^0} \to \pi \pi \pi^0$. Using data collected by BaBar with an integrated luminosity of about 203 $fb^{-1}$, we measure the branching fraction of this decay chain and its decay rate asymmetry. This mode can be used to measure the weak phase gamma through the interferences between the $b\to u \bar{c} d$ and $b\to c \bar{u} d$ decays.