Heavy-flavor-conserving hadronic weak decays of heavy baryons

Abstract: More than two decades ago, we studied heavy-flavor-conserving weak decays of heavy baryons within the framework that incorporates both heavy-quark and chiral symmetries. In view of the first observation of Ξ_b ⁻ → Λ_b ⁰π⁻ by LHCb recently, we have reexamined these decays and presented updated predictions. The predicted rates for Ξ_b ⁻ → Λ_b ⁰π⁻ in the MIT bag and diquark models are consistent with experiment. The major theoretical uncertainty stems from the evaluation of baryon matrix elements. The branching fraction of Ξ_c → Λ_cπ is predicted to be of order 10⁻⁴. It is suppressed relative to (Formula presented.) owing to the shorter lifetime of Ξ_c relative to Ξ_b and the destructive nonspectator W-exchange contribution. The kinematically accessible weak decays of the sextet heavy baryon Ω_Q are Ω_Q → Ξ_Qπ. Due to the absence of the (Formula presented.) transition in the heavy quark limit and the (Formula presented.) transition in the model calculations, Ω_Q → Ξ_Qπ vanish in the heavy quark limit.