Nonfactorizable charming loops in FCNC B decays versus B-decay semileptonic form factors

We compare a nonfactorizable charming-loop correction to an exclusive FCNC B decay given in terms of the three-particle Bethe-Salpeter amplitude (3BS) of the B meson, (0|(q) over bar (x)G(mu nu)(z)b(0)|B(p)), with the corresponding correction to the B-meson semileptonic form factor. In spite of certain similarities, these two corrections are shown to have substantial differences: the form-factor correction is dominated by the collinear light-cone configuration of 3BS (z(mu) = ux(mu), 0 < u < 1, x(2) = 0); in contrast, the FCNC amplitude is dominated by a different configuration with noncollinear arguments [x(2) = 0, z(2) = 0, but (x - z)(2) not equal 0 (i.e., z(mu) not equal ux(mu))].