Cabibbo-allowed nonleptonic weak decays of charmed baryons

Cabibbo-allowed nonleptonic weak decays of charmed baryons Λc⁺, Ξc0A, Ξc+A, and Ωc⁰ into an octet baryon and a pseudoscalar meson are analyzed. The nonfactorizable contributions are evaluated under the pole approximation, and it turns out that the s-wave amplitudes are dominated by the low-lying 1/2^- resonances, while p-wave ones are governed by the ground state 1/2⁺ poles. The MIT bag model is employed to calculate the coupling constants, form factors, and baryon matrix elements. Our conclusions are the following: (i) s waves are no longer dominated by commutator terms; the current-algebra method is not applicable to parity-violating amplitudes. (ii) Nonfactorizable W-exchange effects are generally important; they can be comparable to and sometimes even dominate over factorizable contributions, depending on the decay modes under consideration. (iii) The large-Nc approximation for factorizable amplitudes also works in the heavy baryon sector and it accounts for the color nonsuppression of Λc⁺{→}pK⁰ relative to Λc⁺{→}{Λ}π⁺. (iv) A measurement of the decay rate and the sign of the {α} asymmetry parameter of certain proposed decay modes will help discern various models. (v) p waves are the dominant contributions to the decays Λc⁺{→}Ξ⁰{K}⁺$ and ${{{Ξ}}}c0A→{{{Σ}}}⁺K^-, but they are subject to a large cancellation; this renders present theoretical predictions on these two channels unreliable.