Threshold effects in excited charmed baryon decays

Motivated by recent results on charmed baryons from CLEO and FOCUS, we reexamine the couplings of the orbitally excited charmed baryons. Because of its proximity to the Σ_cπ threshold, the strong decays of the Λ⁺_c(2593) are sensitive to finite width effects. This distorts the shape of the invariant mass spectrum in Λ⁺_c1→Λ⁺_cπ⁺π^- from a simple Breit-Wigner resonance, which has implications for the experimental extraction of the Λ⁺_c(2593) mass and couplings. We perform a fit to unpublished CLEO data which gives M(Λ⁺_c(2593))-M(Λ⁺_c)=305.6±0.3 MeV and h²₂=0.24^+0.23_-0.11, with h₂ the Λ_c1→Σ_cπ strong coupling in the chiral Lagrangian. We also comment on the new orbitally excited states recently observed by CLEO.