In this work, we give a detailed discussion for QCD factorization involved
in the complete chirally enhanced power corrections in the heavy quark limi
t for B decays to two light pseudoscalar mesons. and present some detailed
calculations of radiative corrections at the order of alpha (s). We point o
ut that the infrared finiteness of the vertex corrections in the chirally e
nhanced power corrections requires twist-3 light-cone distribution amplitud
es (LCDAs) of the light pseudoscalar symmetric. However, even in the symmet
ric condition. there is also a logarithmic divergence from the end points o
f the twist-3 LCDAs in the hard spectator scattering. We point out that the
decay amplitudes of B --> PP predicted by QCD factorization are really fre
e of the renormalization scale dependence, at least at the order of alpha (
s). At last, we briefly compare the QCD factorization with the generalized
factorization and PQCD method.