Light-cone momentum distribution of heavy quarks

It is shown how to implement the heavy-quark limit in light-cone quantization. This allows one to derive constraints on the end-point behavior of heavy-quark distributions measured in inclusive semileptonic decays of hadrons containing heavy quarks. The total momentum carried by the light quarks and gluons is related to the hadron excitation energy. The small-z asymptotics of the momentum distribution of the light constituents follows from quark counting rules.