Nonfactorizable charm-loop effects in exclusive FCNC B-decays

This talk presents our recent results [1] on nonfactorizable charm-loop contributions to the amplitudes of rare exclusive $B$-decays induced by flavour-changing neutral currents (FCNC). We show that such contributions induced by a soft-gluon emission from the charm-quark loop may be expressed via three-particle quark-antiquark-gluon distribution amplitude (3DA) of the $B$-meson, $\langle 0|\bar q(x)G_{\mu\nu}(y)b(0)|B(p)\rangle$, and the knowledge of the full functional dependence of the latter quantity on the variable $(x-y)^2$ is necessary for a proper summation of potentially large terms $O\left(\left(\Lambda_{QCD}m_b/m_c^2\right)^n\right)$ in the amplitudes of FCNC $B$-decays.