B ->pi pi,K pi decays in the QCD improved factorization approach - art. no. 094020

Motivated by recent measurements, we investigate B-->pi pi ,K pi decay mode s in the framework of QCD improved factorization, which was recently propos ed by Beneke et at We find that all the measured branching ratios are well accommodated in the reasonable parameter space except for B-->K(o)pi (o). W e also discuss in detail the strong penguin contributions and the O(alpha ( s)) corrections to the chirally enhanced terms. We find that the weak phase gamma lies in the region 120 degrees < <gamma> <240<degrees>, which is mai nly constrained by B-->pi (-)pi (+).