Photonic penguins at two loops and mt-dependence of BR[B→Xsl+l−] Original Research Article

We calculate two-loop matching conditions for all the operators that are relevant to B→Xsl+l− decay in the Standard Model. In effect, we are able to remove the ±16% uncertainty in the decay spectrum, which was mainly due to the renormalization-scale dependence of the top-quark mass. We find 1.46×10−6 for the branching ratio integrated in the domain ml+l−2/mb2∈[0.05,0.25], for l=e or μ. There remains around 13% perturbative uncertainty in this quantity, while the non-perturbative effects are expected to be smaller.