Nonfactorizable charming loops in exclusive FCNC $B$ decays

We compare (i) nonfactorizable charm-quark loops in exclusive FCNC B-decays and (ii) three-particle contributions to the amplitude of semileptonic B-decay. Both amplitudes are given in the heavy-quark limit, $m_b\to \mathrm{\infty }$, by a convolution of a hard kernel and a three-particle wave function of the $B$-meson, $⟨0\mathrm{\mid }\bar{q}(x)G_{\mu \nu }(z)b(0)\mathrm{\mid }B(p)⟩$. An essential difference between the two amplitudes is that the amplitude of semileptonic $B$-decay involves this 3-particle wave function in a collinear light-cone configuration, whereas the amplitude of nonfactorizable charm in FCNC $B$-decays involves this 3-particle wave function in a double collinear light-cone configuration.