A model independent determination of vertical bar V-ub vertical bar

It is shown that measuring the lepton invariant mass spectrum in inclusive semileptonic (B) over bar --> X(u)l<(nu)over bar> decay yields a model inde pendent determination of \V-ub\. Unlike the lepton energy and hadronic inva riant mass spectra, nonperturbative effects are only important in the reson ance region, and play a parametrically suppressed role when d Gamma/dq(2) i s integrated over q(2) > (m(B) - m(D))(2), which is required to eliminate t he charm background. Perturbative and nonperturbative corrections are prese nted to order alpha(s)(2)beta(0) and Lambda(QCD)(2)/m(b)(2), and the Lambda (QCD)(3)/m(b)(3) corrections are used to estimate the uncertainty in our re sults. The utility of the (B) over bar --> X(s)l(+)l(-) decay rate above th e psi(2S) resonance is discussed. (C) 2000 Elsevier Science B.V. All rights reserved.