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

## TL;DR

This paper reevaluates the uncertainties in the $ar B o X_s o ext{gamma}$ decay rate and CP asymmetry, focusing on resolved photon contributions related to non-local operators, using recent HQET parameter knowledge.

## Contribution

It provides a new assessment of resolved photon contributions to $ar B o X_s o ext{gamma}$ decay, incorporating recent advances in HQET parameters.

## Key findings

- Revised estimates of the decay rate uncertainties.
- Updated predictions for CP asymmetry.
- Identification of dominant contributions to uncertainties.

## Abstract

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. We use recent progress in our knowledge of these parameters to reevaluate the resolved photon contribution to $\bar B\to X_s\gamma$ total rate and CP asymmetry.