Role of “Intrinsic Charm” in Semi-Leptonic B-Meson Decays

We discuss the role of so-called “intrinsic-charm” operators in semi-leptonic B-meson decays, which appear first at order 1/mb in the heavy quark expansion. We show by explicit calculation that – at scales μ ≤ mc – the contributions from “intrinsiccharm” effects can be absorbed into short-distance coefficient functions multiplying, for instance, the Darwin term. Then, the only remnant of “intrinsic charm” are logarithms of the form ln(mc/m 2 b), which can be resummed by using renormalizationgroup techniques. As long as the dynamics at the charm-quark scale is perturbative, αs(mc) 1, this implies that no additional non-perturbative matrix elements aside from the Darwin and the spin-orbit term have to be introduced at order 1/mb . Hence, no sources for additional hadronic uncertainties have to be taken into account. Similar arguments may be made for higher orders in the 1/mb expansion. ar X iv :0 80 5. 09 71 v2 [ he pph ] 2 2 A ug 2 00 8