How good is the factorization approach in charm decays?

An analysis of the factorization approach in charm hadronic decays is carried out by using the spectral-functions method and by exploiting the updated information on the semileptonic processes of both the D meson and the τ lepton. Not only the two-body but also the multiparticle exclusive decays can be computed for the first time. While for some channels agreement with experiment is somewhat acceptable, within a factor of 2, much larger variance is found for other modes: D0→K-a1+(1260), D0→K-*π+, D0→K-ππππ