Factorization of heavy-to-light form factors in soft-colline(11)

Heavy-to-light transition form factors at large recoil energy of the light meson have been conjectured to obey a factorization formula, where the set of form factors is reduced to a smaller number of universal form factors up to hard-scattering corrections

Figure2:Divergencestructureoftheintegral(3)anditso -shell,masslessver-

sionwhenexpandedbyregions.Thearrowsindicatethedivergencesindi erent

regionsthatarerelatedandcanceleachother.Thedashedlinesmarkthevarious

factorizationsteps.