Reevaluating Uncertainties in $\bar B\to X_s\gamma$ Decay

Understand

The rare decay $\bar B\to X_s\gamma$ is an important probe of physics beyond the standard model.

• The largest uncertainty on the total rate and the CP asymmetry arises from resolved photon contributions.
• These appear first at order $1/m_b$ and are related to operators other than $Q_{7\gamma}$ in the effective weak Hamiltonian.
• One of the three leading contributions, $Q^q_1-Q_{7\gamma}$, is described by a non-local function whose moments are related to HQET parameters.