Non-factorizable contributions in B decays revisited
  Two-body decays of B mesons are studied by decomposing their amplitude into a sum of factorizable and non-factorizable ones. The former is estimated by using the naive factorization while the latter is calculated by using a hard pion (or kaon) approximation in the infinite momentum frame. It is seen that the non-factorizable contribution is small but not negligible in color favored decays while it is more important in color mismatched decays. 
K. Terasaki