Abstract
Interference between the photonic dipole operator Q7 and the current-current operators Q1,2 gives one of the most important QCD corrections to the (\( \overline{B}\to {X}_s\gamma \) decay rate. So far, the \( \mathcal{O}\left({\alpha}_{\mathrm{s}}^2\right) \)) part of this correction has been known in the heavy charm quark limit only (m c ≫ m b /2). Here, we evaluate this part at m c = 0, and use both limits in an updated phenomenological study. Our prediction for the CP- and isospin-averaged branching ratio in the Standard Model reads \( {\mathrm{\mathcal{B}}}_{s\gamma}^{\mathrm{SM}}=\left(3.36\pm 0.23\right)\times 1{0}^{-4} \) for E γ > 1.6 GeV.
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Czakon, M., Fiedler, P., Huber, T. et al. The (Q7, Q1,2) contribution to \( \overline{B}\to {X}_s\gamma \) at \( \mathcal{O}\left({\alpha}_{\mathrm{s}}^2\right) \). J. High Energ. Phys. 2015, 168 (2015). https://doi.org/10.1007/JHEP04(2015)168
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DOI: https://doi.org/10.1007/JHEP04(2015)168