Usingb→sγto probe top quark couplings

Possible anomalous couplings of the top quark to on-shell photons and gluons are constrained by the recent results of the CLEO Collaboration on both inclusive and exclusive radiative $B$ decays. We find that the process $b\to s\gamma$ can lead to reasonable bounds (of order a few ×${10}^{-16\mathrm{}}$ e cm) on both the anomalous electric and magnetic dipole moments of the top quark. Essentially no limits are obtained on the corresponding chromoelectric and chromomagnetic moments, which enter the expression for the decay rate only through operator mixing.