Second Order Power Corrections in the Heavy Quark Effective Theory II. Baryon Form Factors

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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*.