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Heavy-Flavor-Conserving Hadronic Weak Decays of Heavy Baryons

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 $Ξ_b^-\toΛ_b^0π^-$ by LHCb recently, we have reexamined these decays and presented updated predictions. The predicted rates for $Ξ_b^-\toΛ_b^0π^-$ 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 $Ξ_c\toΛ_cπ$ is predicted to be of order $10^{-4}$. It is suppressed relative to $Br(Ξ_b\toΛ_bπ)$ 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 $Ω_Q\toΞ_Qπ$. Due to the absence of the $B_6-B_{\bar 3}$ transition in the heavy quark limit and the $B_6-B_6$ transition in the model calculations, $Ω_Q\toΞ_Qπ$ vanish in the heavy quark limit.