Vub from the hadronic invariant mass spectrum in semileptonic B decay

The hadronic invariant mass spectrum for the inclusive charmless semileptonic decay B -> X_u e v_e is studied. Particular attention is paid to the region s_H < m²_D, which may be useful for extracting the value of V_ub. The sensitivity of the spectrum to the parameter Λ --- m_B- m_b is explored. Perturbative QCD corrections to dΓ/ds_H of order α²_sβ₀ are calculated. For s_H ~ Λ m_b 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 V_ub is explored.