arXiv:1512.01276v2 [hep-ph] 21 Feb 2016 February, 2016 Heavy-Flavor-Conserving Hadronic Weak Decays of Heavy Baryons Hai-Yang Cheng 1 , Chi-Yee Cheung 1 , Guey-Lin Lin 2 , Yeu-Chung Lin 3 , Tung-Mow Yan 4 , Hoi-Lai Yu 1 1 Institute of Physics, Academia Sinica Taipei, Taiwan 115, Republic of China 2 Institute of Physics, National Chiao Tung University Hsinchu 30010, Taiwan, Republic of China 3 Department of Physics, National Taiwan University Taipei 10617, Taiwan, Republic of China 4 Laboratory for Elementary Particle Physics, Cornell University Ithaca, NY 14853, USA 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 0 b π − by LHCb recently, we have reexamined these decays and presented updated predictions. The predicted rates for Ξ − b → Λ 0 b π − 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 c π is predicted to be of order 10 −4 . It is suppressed relative to B(Ξ b → Λ b π) 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 Q π. Due to the absence of the B 6 −B¯ 3 transition in the heavy quark limit and the B 6 −B 6 transition in the model calculations, Ω Q → Ξ Q π vanish in the heavy quark limit. 1