Updated NNLO QCD predictions for the weak radiative B-meson decays

TL;DR

This paper updates the Standard Model predictions for the inclusive branching ratios of weak radiative B-meson decays at NNLO QCD, incorporating recent calculations and nonperturbative effects, and derives implications for new physics constraints.

Contribution

The paper provides the most recent NNLO QCD predictions for B-meson radiative decays, including updated perturbative and nonperturbative effects, improving the precision of Standard Model estimates.

Findings

Predicted B_{s gamma} = (3.36 ± 0.23) × 10^{-4}

Predicted B_{d gamma} = (1.73^{+0.12}_{-0.22}) × 10^{-5}

New lower bound on charged Higgs mass: M_{H^+} > 480 GeV

Abstract

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(alpha_s^2) and lower-order perturbative corrections that have been calculated after 2006. New estimates of nonperturbative effects are taken into account, too. For the CP- and isospin-averaged branching ratios, we find B_{s gamma} = (3.36 +_ 0.23) * 10^-4 and B_{d gamma} = 1.73^{+0.12}_{-0.22} * 10^-5, for E_gamma > 1.6GeV. Both results remain in agreement with the current experimental averages. Normalizing their sum to the inclusive semileptonic branching ratio, we obtain R_gamma = ( B_{s gamma} + B_{d gamma})/B_{c l nu} = (3.31 +_ 0.22) * 10^-3. A new bound from B_{s gamma} on the charged Higgs boson mass in the two-Higgs-doublet-model II reads M_{H^+} > 480 GeV at 95%C.L.