HQET and Form Factor Effects in B {r_arrow} K{sup (*)} {ell}{sup +}{ell}{sup {minus}}

We examine the rates for the exclusive decays B {r_arrow} K* {ell}{sup +}{ell}{sup {minus}}. We use the scaling predictions of the heavy quark effective theory to extract the necessary form factors from fits to various combinations of data. These data include the D {r_arrow} K*{ell}{nu} semileptonic decays, as well as the nonleptonic decays B{r_arrow}K*{psi}{prime} and the rare decay B {r_arrow} K*{gamma}. We use different parametrizations of form factors, and find that integrated decay rates are not very sensitive to the forms chosen. However, the decay spectra and the forward-backward asymmetry in B {r_arrow} K*{ell}{sup +}{ell}{sup {minus}} are sensitive to the forms chosen for the form factors, while the lepton polarization asymmetry in {bar B}{sup 0} {r_arrow} {bar K}{sup 0} {mu}{sup +} {mu}{sup {minus}} is largely independent of the choice of form factors. Contributions from charmonium resonances dominate the spectra and integrated rates. In our best scenario, we find Br({bar B}{sup 0}) {r_arrow} {bar K}{sup 0} {mu}{sup +}{mu}{sup {minus}} = 2.0 {+-} 0.3 times 10{sup {minus}6} and Br({bar B}{sup 0} {r_arrow} {bar K}*{sup 0} {mu}{sup +} {mu}{sup {minus}}) = 8.1 {+-} 2.0 x 10{sup {minus}6}. We also make predictions for other polarization observables in these decays