IMPLICATIONS OF B-]S-GAMMA ON THE ANOMALOUS ELECTROMAGNETIC COUPLINGS OF GAUGE BOSONS AND QUARKS

We reexamine the possible deviations from the standard model on the decay b --> s gamma within the context of an effective Lagrangian approach. We consider dimension-6 operators which are SU(2)(L) X U(1)(Y) gauge invariant and contribute to this decay mode at tree- and one-loop level. Using the recent results of the CLEO Collaboration on radiative B decays, we get constraints on the anomalous electromagnetic couplings of the W boson and the quarks t, c, u. We get an improved constraint on the anomalous magnetic moment of the quark t as compared to that obtained with only U(1)(EM) gauge-invariant dimension-6 operators. As a byproduct, we obtain also a bound on the decay width of t --> c gamma.