Higher-order power-suppressed nonperturbative corrections to b-bar to X_s gamma

Determine the potentially sizeable higher-order effects in the power-suppressed, nonperturbative corrections to the Standard-Model prediction for the inclusive radiative decay \bar B\to X_s\gamma, thereby reducing the associated theoretical uncertainty.

Background

The paper presents an updated Standard-Model prediction for the branching ratio of the inclusive radiative decay \bar B\to X_s\gamma with a photon-energy cut of 1.6 GeV. The quoted total uncertainty is approximately 4%, obtained by combining parametric and higher-order uncertainties in quadrature.

Although the perturbative scale dependence is reported to be much smaller than 3%, the paper retains a 3% higher-order uncertainty because power-suppressed, nonperturbative corrections may receive sizeable contributions beyond the orders currently under control. The magnitude of these effects is therefore unresolved and limits the precision of the prediction.