Key distributions for charmless semileptonic B decay

We present theoretical predictions for a few phenomenologically interesting distributions in the semileptonic b → u decays which are affected by Fermi motion. The perturbative effects are incorporated at the one-loop level and appear to be very moderate. Our treatment of Fermi motion is based directly on QCD, being encoded in the universal distribution function F(x). The decay distributions in the charged lepton energy, invariant mass of hadrons, hadron energy, and q2 are given. We note that typically about 90% of all decay events are expected to have MX < MD; this feature can be exploited in the determination of |Vub|.