Direct CP Asymmetry in B->X_{s,d}+gamma Decays

TL;DR

This paper reveals that the CP asymmetry in B->X_{s,d}+gamma decays is dominated by non-perturbative effects, challenging previous perturbative predictions and proposing a new test for new physics via asymmetry differences in charged and neutral B-mesons.

Contribution

The study demonstrates the dominance of non-perturbative effects in CP asymmetry and introduces a novel test for new physics through asymmetry differences in B-meson decays.

Findings

CP asymmetry is dominated by non-perturbative effects.

Standard model predicts about 0.5% asymmetry.

Difference in asymmetries between charged and neutral B-mesons offers a new physics test.

Abstract

The CP asymmetry in inclusive B->X_{s,d}+gamma decays is an important probe of new physics. The theoretical prediction was thought to be of a perturbative origin, and in the standard model, to be about 0.5 percent. In a recent work with M. Benzke, S.J. Lee and M. Neubert, we have shown that the asymmetry is in fact dominated by non-perturbative effects. Since these are hard to estimate, it reduces the sensitivity to new physics effects. On the other hand, these new non-perturbative effects suggest a new test of new physics by looking at the difference of the CP asymmetries in charged versus neutral B-meson decays.