Non-universal effects in semi-inclusive B decays

We show that most spectra in the semileptonic decay B -> X-u + l + nu(l), such as for example the distribution in the light-cone momentum p(+) E-X - vertical bar(p) over barx vertical bar recently considered, do not have the same long-distance structure of the photon spectrum in the radiative decay B -> X-s + gamma. On the contrary, the semileptonic distribution in the final hadron energy E-X is connected to the radiative spectrum via short-distance factors only. The E-X distribution also has a specific infrared structure known as the "Sudakov shoulder". We also discuss an explicit check of the resummation formula for the semileptonic decays, based on a recent second-order computation.