Quasi-inclusive and exclusive decays of B to η′

We consider the effective Hamiltonian of four quark operators in the Standard Model in the exclusive and quasi-inclusive decays of the type B --> K(*)eta', B --> eta'X-s, where X-s contains a single Kaon. Working in the factorization assumption we find that the four quark operators can account for the recently measured exclusive decays B --> eta'(eta)K and B --> K pi for appropriate choice of form factors but cannot explain the large quasi-inclusive rate. (C) 1998 Elsevier Science B.V.