Determination of weak phases ${\varphi }_2$ and ${\varphi }_3$ from $B\to \pi \pi ,K\pi$ in the pQCD method

We look at two methods to determine the weak phases ${\varphi }_2$ and ${\varphi }_3$ from $B\to \pi \pi$ and $K\pi$ decays within the perturbative QCD approach. We obtain quite interesting bounds on ${\varphi }_2$ and ${\varphi }_3$ from recent experimental measurements in asymmetric B-factory: $55^o \leq \phi_2 \leq 100^o$and$51^o \leq \phi_3 \leq 129^o$. Specially we predict the possibility of large direct CP violation effect in $B^0\to {\pi }^{+}{\pi }^{-}$ decay with $A_{cp}^{dir}(B\to {\pi }^{+}{\pi }^{-})=(23\pm 7)$ %.