EXCLUSIVE RARE B-DECAYS IN THE HEAVY QUARK LIMIT

We calculate the rare B-decays B --> K*gamma and B --> (K, K*)llBAR (l = e, mu, nu) in the limit when the quark masses m(b), m(c) and m(s) are considered heavy. In this limit, the semileptonic decays B --> Dl-nu-l, B --> D*l-nu-l, D --> Kl-nu-l, D --> K*l-nu-l and the mentioned rare B-decays are related. Experimental data on the semileptonic decays then provide both input information for the rare B-decays as well as an estimate of the error of our approximation.