B→Kl+l- and other rare B-meson decays

We calculate the rate and the CP-nonconservation asymmetry for the rare decay B→Kl+l- (l = e or μ). In the standard model with three generations we find the branching ratio to be of the order of 10/sup -6/, and the CP-nonconservation asymmetry at most about 1%. The decay proceeds via the flavor-changing loop structure of the standard model, and unlike K→πe+e- suffers few uncertainties and can therefore be used as a probe of new physics. We also comment on other rare decay modes of the B meson