Precision Global Determination of the $B→X_sγ$ Decay Rate

Abstract

We perform the first global fit to inclusive $B→X_sγ$ measurements using a model-independent treatment of the nonperturbative $b$-quark distribution function, with next-to-next-to-leading logarithmic resummation and $O(α_s^2)$ fixed-order contributions. The normalization of the $B→X_sγ$ decay rate, given by $|C_7^{incl}V_{tb}V_{ts}^*|^2$, is sensitive to physics beyond the standard model (SM). We determine $|C_7^{incl}V_{tb}V_{ts}^*|$ = $(14.77±0.51_{fit}±0.59_{theory}±0.08_{param})×10^{-3}$, in good agreement with the SM prediction, and the $b$-quark mass $m_b^{1S}$ = $(4.750±0.027_{fit}±0.033_{theory}±0.003_{param})$ GeV. Our results suggest that the uncertainties in the extracted $B→X_sγ$ rate have been underestimated by up to a factor of 2, leaving more room for beyond-SM contributions