KEY DISTRIBUTIONS FOR CHARMLESS SEMILEPTONIC B-DECAY

We present theoretical predictions for a few phenomenologically intere sting distributions in the semileptonic b --> u decays which are affec ted 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 distri bution function F(x). The decay distributions in the charged lepton en ergy, invariant mass of hadrons, hadron energy, and q(2) are given. We note that typically about 90% of all decay events are expected to hav e M-X < M-D; this feature can be exploited in the determination of \V- ub\. (C) 1998 Published by Elsevier Science B.V.