Semileptonic decays of heavy Λ's into excited baryons

Abstract

We use the heavy quark effective theory to investigate the form factors that describe the semileptonic decays Λ b → Λ c ∗ and Λ c + → Λ ∗, both to leading order and to order 1/ m c in the effective lagrangian. In leading order, we find that a single form factor is needed in the former case, and that two are needed for each heavy → light transition. We also investigate these transitions to order 1/ m c in the heavy quark lagrangian, and find that the results to this order are also quite simple, although the number of form factors needed increases. We briefly discuss the relationship between our form factors and the recently developed Bjorken-Dunietz-Taron sum rules for inclusive semileptonic decays of heavy baryons.