Reevaluating Uncertainties in $\bar{B}\rightarrow X_s\gamma$

TL;DR

This paper refines the understanding of uncertainties in the rare decay X_sgamma by leveraging recent knowledge of heavy quark effective theory parameters to improve predictions of decay rate and CP asymmetry.

Contribution

It provides a new analysis constraining the dominant uncertainties in X_sgamma decay using updated HQET parameters, especially for the non-local operator contributions.

Findings

Reduced uncertainties in decay rate predictions.

Improved constraints on CP asymmetry.

Enhanced understanding of heavy quark expansion effects.

Abstract

The rare inclusive decay $\bar{B}\rightarrow X_s\gamma$ is an important probe of physics beyond the standard model. The largest uncertainty on the decay rate and CP asymmetry comes from operators that appear at order $1/m_b$ in the heavy quark expansion. One of the three leading contributions in the heavy quark expansion, $Q_1^q-Q_{7\gamma}$ 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 better constrain their contributions to the total rate and CP asymmetry.