Light Rays of New Physics: CP Violation in B -> Xs gamma Decays

Abstract

The observation of a sizable CP asymmetry in the inclusive decays B -> Xs gamma would be a clean signal of New Physics. In the Standard Model, this asymmetry is below 1 % in magnitude. In extensions of the Standard Model with new CP-violating couplings, large asymmetries are possible without conflicting with the experimental value of the B -> Xs gamma branching ratio. In particular, large asymmetries arise naturally in models with enhanced chromo-magnetic dipole transitions. Some generic examples of such models are explored and their implications for the semileptonic branching ratio and charm yield in B decays discussed.