Differential distributions in semileptonic decays of heavy flavors in QCD

A generalization of the operator product expansion is used to find the differential distributions in the inclusive semileptonic weak decays of heavy flavors in QCD. In particular, the double distribution in electron energy and invariant mass of the lepton pair is calculated. We are able to calculate the distributions in an essentially model-independent way as a series in $m_Q^{-1\mathrm{}}$ where $m_Q$ is the heavy quark mass. All effects up to $m_Q^{-2\mathrm{}}$ are included.