ИСТИНА

We present the first theoretical calculation of nonfactorizable charm-quark loop contributions to the Bs→γl+l- amplitude. We calculate the relevant form factors, HA,VNF(k′2,k2), and provide convenient parametrizations of our results in the form of fit functions of two variables, k′2 and k2, applicable in the region below hadron resonances, k′2<MJ/ψ2 and k2<Mϕ2. We report that factorizable and nonfactorizable charm contributions to the Bs→γl+l- amplitude have opposite signs. To compare the charm and the top contributions, it is convenient to express nonfactorizable charming loop contribution as a nonuniversal (i.e., dependent on the reaction) q2-dependent correction ΔNFC7(q2) to the Wilson coefficient C7. For the Bs→γl+l- amplitude, the correction is found to be positive, ΔNFC7(q2)/C7>0.