Determining weak phases from theB→ππ,Kπdecays

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 an exact solution from the $B\to \pi \pi$ data and an exact 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 ${\varphi }_2\approx {90}^o$ and ${\varphi }_3\approx {60}^o$ are consistent with the global unitarity triangle fit.