2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/36837The b --> s gamma transition proceeds by a loop ``penguin'' diagram. It may be used to measure precisely the couplings of the top quark and to search for the effects of any new particles appearing in the loop. We present a preliminary measurement of the branching fraction of the exclusive decay, B^0 --> K^{*0}gamma. We use 8.6 x 10^6 B-anti-B decays to measure B(B^0 --> K^{*0}gamma) = (5.4+/-0.8+/-0.5) x 10^{-5}.17 pages, 5 postscript figures, contributed paper to ICHEP2000High Energy Physics - Experimenttext