Vub from the Hadronic Invariant Mass Spectrum in Semileptonic B Decay

The hadronic invariant mass spectrum for the inclusive charmless semileptonic decay B → Xu e ν̄e is studied. Particular attention is paid to the region sH < mD, which may be useful for extracting the value of |Vub|. The sensitivity of the spectrum to the parameter Λ̄ ≡ mB − mb is explored. Perturbative QCD corrections to dΓ/dsH of order α 2 sβ0 are calculated. For sH ∼ Λ̄mb nonperturbative QCD effects are important and the shape of the invariant mass spectrum is controlled by the B meson matrix element of an infinite sum of local operators. The utility of the hadronic mass spectrum for extracting |Vub| is explored.