Updated Next-to-Next-to-Leading-Order QCD Predictions for the Weak Radiative B -Meson Decays

Weak radiative decays of the B mesons belong to the most important flavor changing processes that provide constraints on physics at the TeV scale. In the derivation of such constraints, accurate standard model predictions for the inclusive branching ratios play a crucial role. In the current Letter we present an update of these predictions, incorporating all our results for the O (α_s²) and lower-order perturbative corrections that have been calculated after 2006. New estimates of nonperturbative effects are taken into account, too. For the C P - and isospin-averaged branching ratios, we find B_{s γ}=(3.36 ±0.23 )×10^-4 and B_{d γ}=(1.7 3_-0.22^+0.12) ×10^-5 , for E_γ>1.6 GeV . Both results remain in agreement with the current experimental averages. Normalizing their sum to the inclusive semileptonic branching ratio, we obtain R_γ≡(B_{s γ}+B_{d γ}) /B_{c ℓν}=(3.31 ±0.22 )×10^-3 . A new bound from B_{s γ} on the charged Higgs boson mass in the two-Higgs-doublet-model II reads M_H^±>480 GeV at 95% C.L.