QCD ENHANCEMENT OF B-]S-GAMMA DECAY FOR A HEAVY TOP QUARK

An effective five-quark hamiltonian for b --> s decay processes is derived by integrating out a heavy top quark with m(t)2 much greater than m(w)2 from the minimal six-quark standard model. The leading strong interaction corrections to this hamiltonian are then determined in an effective field theory computation. The renormalization group running of the operators in the effective hamiltonian between a top quark scale of 250 GeV and the W-scale is found to be significant and enhances the inclusive rate for the rare weak decay BBAR --> X(s)gamma by about 14%.