$1/m_b$ Corrections in the ACCMM Model for Inclusive Semileptonic B Decay

We re-examine the model of Altarelli, Cabibbo, Corb\`{o}, Maiani and Martinelli for inclusive semileptonic B decay, in the light of recent calculations in heavy quark effective theory. The model can be shown to have no~$1/m_b$ corrections, with a suitable definition of the b quark mass~$m_b$. However, we find that the structure of the $1/m_b^2$~terms is incompatible with the predictions of heavy quark effective theory. The numerical significance of this discrepancy is discussed.