Bounds on the CP Asymmetry in $b\to s\gamma$ Decays

TL;DR

This paper measures the CP asymmetry in b to s gamma decays, providing limits that constrain some non-Standard Model theories while remaining consistent with the Standard Model.

Contribution

The paper presents the first measurement of CP asymmetry in b to s gamma decays with improved precision, setting bounds that challenge certain new physics models.

Findings

CP asymmetry A_CP is measured to be approximately -0.079 with uncertainties.

At 90% confidence, A_CP is between -0.27 and +0.10.

Results exclude some extreme non-Standard Model predictions.

Abstract

We have measured the CP asymmetry A_CP = [BF(b -> s gamma) - BF(bbar -> sbar gamma)]/ [BF(b -> s gamma) + BF(bbar -> sbar gamma)] to be A_CP = (-0.079 +/- 0.108 +/- 0.022)(1.0 +/- 0.030), implying that, at 90% confidence level, A_CP lies between -0.27 and +0.10. These limits rule out some extreme non-Standard Model predictions, but are consistent with most, as well as with the Standard Model.