Analysis of the hadronic invariant mass spectrum in inclusive charmless semileptonic B decays

We analyze the hadronic invariant mass spectrum in inclusive charmless semileptonic B meson decays in a QCD-based approach. The decay width is studied as a function of the invariant mass cut. We examine their sensitivities to the parameters of the theory. The theoretical uncertainties in the determination of \ V-ub \ from the hadronic invariant mass spectrum are investigated. A strategy for improving the theoretical accuracy in the value of \ V-ub \ is described.