$B \to \gamma \gamma$ in an ACD model

Abstract

We present a full calculation of the amplitudes for $B_{d[s]} \to \gamma \gamma$ in a simple ACD model that extends an incomplete one in a previous paper. We find cancellations between the contributions from different KK towers and a small decrease relative to the SM predictions. It is conjectured that radiative QCD corrections might actually lead to an enhancement in the branching ratios and {\bf CP} asymmetries, but no more than modest ones.