title: Long-distance dominance of the CP asymmetry in B→X(s,d)γ decays.
abstract: We show that in the standard model the parametrically leading (by a factor 1/α(s)) contribution to the inclusive CP asymmetry in B→X(s,d)γ decays arises from a long-distance effect in the interference of the electromagnetic dipole amplitude with the amplitude for an up-quark penguin transition accompanied by soft gluon emission. Using model estimates for the associated hadronic parameter Λ(17)(u), we predict a value in the range -0.6% < A(X(s)γ)(SM) < 2.8%. In view of current experimental data, a future precision measurement of the flavor-averaged CP asymmetry would signal the presence of new physics only if a value below -2% was found. A cleaner probe of new physics is offered by the difference of the CP asymmetries in charged versus neutral B→X(s,d)γ decays.
authors.affiliation: Institut für Physik (THEP), Johannes Gutenberg-Universität, D-55099 Mainz, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Benzke
authors.forename: Seung J
authors.initials: SJ
authors.lastname: Lee
authors.forename: Matthias
authors.initials: M
authors.lastname: Neubert
authors.forename: Gil
authors.initials: G
authors.lastname: Paz