We compute the two-loop electroweak corrections to the radiative decays of the B meson in the SM. Electroweak effects reduce the Wilson coefficient C7eff(MW) by 2.6% for a light Higgs boson of about 100 GeV and are less important for a heavier Higgs. The leading term of a heavy top expansion of our result differs from the one obtained in the gaugeless approximation where only top quark Yukawa couplings are considered: we discuss the origin of the discrepancy and provide a criterion for the validity of the gaugeless approximation. As a byproduct of the calculation we also obtain the O(α) corrections to the Wilson coefficient of the four-fermion operator Q2. A careful analysis of the interplay between electroweak and QCD effects leads to an overall 2% reduction of the total branching ratio for B→Xsγ due to purely electroweak corrections. For a light Higgs boson, the up-to-date SM prediction is BRγ = (3.29±0.21±0.21) × 10−4.

Electroweak effects in radiative B decays

GAMBINO, Paolo;
2000-01-01

Abstract

We compute the two-loop electroweak corrections to the radiative decays of the B meson in the SM. Electroweak effects reduce the Wilson coefficient C7eff(MW) by 2.6% for a light Higgs boson of about 100 GeV and are less important for a heavier Higgs. The leading term of a heavy top expansion of our result differs from the one obtained in the gaugeless approximation where only top quark Yukawa couplings are considered: we discuss the origin of the discrepancy and provide a criterion for the validity of the gaugeless approximation. As a byproduct of the calculation we also obtain the O(α) corrections to the Wilson coefficient of the four-fermion operator Q2. A careful analysis of the interplay between electroweak and QCD effects leads to an overall 2% reduction of the total branching ratio for B→Xsγ due to purely electroweak corrections. For a light Higgs boson, the up-to-date SM prediction is BRγ = (3.29±0.21±0.21) × 10−4.
2000
0009
001
-
http://iopscience.iop.org/1126-6708/2000/09/001/
Paolo Gambino; Ulrich Haisch
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/104190
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