Bounds on the CP Asymmetry in $b\to sγ$ Decays

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.