Weak phases from the $B\to ππ$, $Kπ$ decays

Recent data of two-body nonleptonic $B$ meson decays allow a topological-amplitude analysis up to the $O(\lambda^2)$ accuracy, where $\lambda$ denotes the Wolfenstein parameter. We find a solution from the $B\to\pi\pi$ data and a solution from the $B\to K\pi$ data, which satisfy the approximate SU(3) flavor symmetry. These solutions indicate that the color-suppressed tree amplitude is large, all other amplitudes can be understood within the standard model, and the weak phases $\phi_2\approx 90^o$ and $\phi_3\approx 60^o$ are consistent with the global unitarity triangle fit.