Second-order power corrections in the heavy-quark effective theory. II. Baryon form factors

The analysis of 1/mQ2 corrections of the previous paper is extended to the semileptonic decays of heavy baryons. We focus on the simplest case, the ground-state ΛQ baryons, in which the light degrees of freedom are in a state of zero total angular momentum. The formalism, while identical in spirit, is considerably less cumbersome than for heavy mesons. The general results are applied to the semileptonic decay Λb→Λclν. An estimate of the leading power corrections to the decay rate at zero recoil, which are of order 1/mQ2, is presented. It is pointed out that a measurement of certain asymmetry parameters would provide a direct measurement of 1/mQ2 corrections. Finally, it is shown how the analysis could be extended to include excited heavy baryons such as the ΣQ and the ΣQ*