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

M Misiak,R Boughezal,J Virto,A Rehman,U Haisch,M Kamiński,M Poradziński,G Ossola,A Ferroglia,M Steinhauser,P Gambino,T Huber,C Greub,H M Asatrian,P Fiedler,T Ewerth,T Schutzmeier,M Czakon

doi:10.1103/physrevlett.114.221801

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(α_{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_{sγ}=(3.36±0.23)×10^{-4} and B_{dγ}=(1.73_{-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_{sγ}+B_{dγ})/B_{cℓν}=(3.31±0.22)×10^{-3}. A new bound from B_{sγ} on the charged Higgs boson mass in the two-Higgs-doublet-model II reads M_{H^{±}}>480 GeV at 95% C.L.

Highlights

We present a generic expression for beyond-standard model (SM) contributions, as well as an updated bound for the charged Higgs boson mass in the two-Higgsdoublet-model II (THDM II)
Summary.—We presented an updated prediction for Bsγ in the SM taking into account all the perturbative and nonperturbative effects worked out after the 2006 publication [15] of the first next-to-nextto-leading order (NNLO) estimate for this quantity
Some of the Oðα2sÞ corrections are still interpolated in mc, but the mc 1⁄4 0 boundary condition comes from an explicit calculation

Summary

The current analysis supersedes our previous one in

[15], which was published in 2006 and has not been updated since . It has been widely considered as a standard reference until now. The time for our update comes only at present because the most recent and technically challenging four-loop calculation of Ref. It has an important effect on the central value of Bsγ. We present a generic expression for beyond-SM contributions, as well as an updated bound for the charged Higgs boson mass in the two-Higgsdoublet-model II (THDM II). Bsγ in the SM.—Radiative B-meson decays are most conveniently described in the framework of an effective theory that arises after decoupling of the W boson and heavier particles.

Bsγ by less than

Findings

Including this contribution in our evaluation of the entire