Determination of the CP violating weak phase $\gamma$ from the Decays $B \to D \pi$

We propose a new method to extract the CP violating weak phase $\gamma$ (the phase of $V_{ub}^*$) in the CKM paradigm of the Standard Model, using $B^- \rightarrow D^0 \pi^- \rightarrow f \pi^-$ and $B^- \rightarrow \bar D^0 \pi^- \rightarrow f \pi^-$ decays, where $f$ are final states such as $K^+ \pi^-$, $K^+ \rho^-$, $K \pi\pi$, {\it etc.} We also study the experimental feasibility of our new method. With possibility of new phases in the CKM matrix, we re-examine some of the previously proposed methods to determine $\gamma$, and find that it would be in principle possible to identify $\gamma$ and a new phase angle $\theta$ separately.