Threshold resummation for nonleptonic B meson decays

We investigate the double logarithmic corrections αsln2x, x being a parton momentum fraction, in two-body nonleptonic B meson decays in collinear factorization theorem of perturbative QCD (PQCD). It is found that these corrections are universal for factorizable amplitudes, i.e., at the leading power, and that their threshold resummation smears the end-point singularities from x→0. The double logarithmic corrections, depending on the topologies of nonfactorizable amplitudes at the subleading power, are negligible due to the color-transparency argument and to the overlap of three meson distribution amplitudes. We show that the PQCD approach to two-body nonleptonic B meson decays respects the factorization assumption in the heavy-quark limit.