A lattice study of the exclusive B --> K$*\gamma$ decay amplitude, using the Clover action at $\beta$ = 6.0

We present the results of a numerical calculation of the B\rightarrow K^* \gamma form factors. The results have been obtained by studying the relevant correlation functions at \beta=6.0, on an 18^3 \times 64 lattice, using the {\rm O(a)}-improved fermion action, in the quenched approximation. From the study of the matrix element \langle K^*\vert \bar s \sigma_{\mu\nu} b \vert B\rangle we have obtained the form factor T_1(0) which controls the exclusive decay rate. The results are compared with the recent results from CLEO. We also discuss the compatibility between the scaling laws predicted by the Heavy Quark Effective Theory (HQET) and pole dominance, by studying the mass- and q^2-dependence of the form factors. From our analysis, it appears that the form factors follow a mass behaviour compatible with the predictions of the HQET and that the q^2-dependence of T_2 is weaker than would be predicted by pole dominance.