Kinetic corrections to (B)over-bar→Xcl(ν)over-bar at one loop

We evaluate the one-loop corrections to the Wilson coefficient of the kinetic operator in the operator product expansion of the differential B -> X(c)l (nu) over bar decay rate. With a moderate cut on the lepton energy, the one-loop terms change the kinetic operator contributions to spectral moments by about 20%. This amounts to a small correction for leptonic and hadronic moments, except for those which vanish at the lowest order, where the effect can be sizable. Together with a two-loop calculation of the leading-power rate and an evaluation of the one-loop corrections to the Wilson coefficient of the chromo-magnetic operator, our results will allow for a high-precision determination of vertical bar V-cb vertical bar and the b- and c-quark masses.