Precision Global Determination of the B→X_{s}γ Decay Rate

Area of Science:

• High Energy Physics
• Particle Physics
• Quantum Chromodynamics

Background:

• The B→Xsγ decay is a sensitive probe for physics beyond the Standard Model (SM).
• Accurate theoretical predictions and experimental measurements are crucial for testing SM and searching for new physics.
• Previous analyses often relied on specific models for nonperturbative effects.

Purpose of the Study:

• To perform the first global fit to inclusive B→Xsγ measurements using a model-independent approach for the b-quark distribution function.
• To determine the normalization of the B→Xsγ decay rate and the b-quark mass with improved precision.
• To assess the impact of uncertainties on the B→Xsγ rate and explore implications for physics beyond the SM.

Main Methods:

• Global fit to inclusive B→Xsγ measurements.
• Model-independent treatment of the nonperturbative b-quark distribution function.
• Inclusion of next-to-next-to-leading logarithmic resummation and O(αs²) fixed-order contributions.

Main Results:

• Determination of |C7inclVtbVts*| = (14.77 ± 0.51fit ± 0.59theory ± 0.08param) × 10⁻³.
• Determination of the b-quark mass mb¹S = (4.750 ± 0.027fit ± 0.033theory ± 0.003param) GeV.
• Results are in good agreement with the SM predictions.

Conclusions:

• The study provides a more robust determination of key parameters in B→Xsγ decays.
• The findings suggest that uncertainties in the extracted B→Xsγ rate may have been underestimated.
• This leaves increased room for contributions from physics beyond the Standard Model.