Semileptonic baryon decays with a heavy quark.

The semileptonic decay of spin-l/2 baryons is examined in the spectator quarkmodel, with special attention given to Ab + A,ev and nb + &ev. The polarization of the virtual-W and of the daughter baryon is also considered, along with the joint angular distribution between the charged lepton and the daughter baryon polarization vector. The Ab decays with about equal mixtures of transverseto longitudinal-W polarization while the fib decays with predominately longitudinalW polarization. These reactions are representative of two qualitatively different classes: decays involving baryons whose spectators are spin-singlets and those whose spectators are spin-triplets. Submitted to Physical Review D * Work supported by Department of Energy contract DE-AC03-76SF00515.