Order 1/m(b)(3) corrections to B->X(c)l(nu)over-bar decay and their implication for the measurement of (Lambda)over-bar and lambda(1)

We compute the order 1/m(b)(3) nonperturbative contributions to the inclusive differential B-->X(c)l (v) over bar decay rate. They are parametrized by the expectation values of two local and four nonlocal dimension-six operators. We use our results to estimate part of the theoretical uncertainties in the extraction of matrix elements <(Lambda)over bar> and lambda(1) from the lepton spectrum in the inclusive semileptonic B decay and find them to be very large. We also compute the 1/m(b)(3) corrections to the moments of the hadronic invariant mass spectrum in this decay, and combine them with the extracted values of <(Lambda)over bar> and lambda(1) to put an upper bound on the branching fraction B(B-->D**l (v) over bar.