The constituent quark model, PCAC consistency and the nonleptonic weak decays of mesons and baryons.

We use the nonperturbative techniques of current algebra and PCAC (partial conservation of axial-vector currents) to compute the nonleptonic weak decays K → 2π and 3π, as well as the two-body and nonresonant three-body decays of the charmed D and F(D(s)) mesons. In the case of two-body decays, the constituent quark model is employed to calculate the resulting unphysical meson-meson reduced matrix elements. Using an analogous current algebra - PCAC prescription, the three-body meson decays are expressed in terms of the previously determined two-body amplitudes. We utilize the pole model to extract baryon-baryon reduced matrix elements from the B → B' π and B'γ weak decays, which are then also computed in the constituent quark model. We make predictions for more than sixty decays with essentially no free parameters and, in most cases, find reasonable agreement with the data