Abstract
The theory of the decays 
→Xsγ and →Xsl+l- is
reviewed. The huge enhancement of the
B→Xsγ branching ratio by
quantum chromodynamics logarithms is
attributed to the renormalization group
evolution of
mb(µ) in the top-quark contribution
to the decay amplitude. The residual µ
dependence of the NLO predictions is
discussed.
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