Strong Decays of Charmed Baryons in Heavy Hadron Chiral Perturbation Theory

Abstract

Strong decays of charmed baryons are analyzed in the framework of heavy hadron chiral perturbation theory (HHChPT) in which heavy quark symmetry and chiral symmetry are synthesized. HHChPT works excellently for describing the strong decays of s-wave charmed baryons. For L=1 orbitally excited states, two of the unknown couplings, namely, $h_2$ and $h_{10}$, are determined from the resonant $Λ_c^+ππ$ mode produced in the $Λ_c(2593)$ decay and the width of $Σ_c(2800)$, respectively. Predictions for the strong decays of the p-wave charmed baryon states $Λ_c(2625)$, $Ξ_c(2790)$ and $Ξ_c(2815)$ are presented. Since the decay $Λ_c(2593)^+\toΛ_c^+ππ$ receives non-resonant contributions, our value for $h_2$ is smaller than the previous estimates. We also discuss the first positive-parity excited charmed baryons. We conjecture that the charmed baryon $Λ_c(2880)$ with $J^P=\frac52^+$ is an admixture of $Λ_{c2}(\frac52^+)$ with and $\tildeΛ''_{c3}(\frac52^+)$; both are L=2 orbitally excited states. The potential model suggests $J^P=\frac52^-$ or $\frac32^+$ for $Λ_c(2940)^+$. Measurements of the ratio of $Σ_c^*π/Σ_cπ$ will enable us to discriminate the $J^P$ assignments for $Λ_c(2940)$. We advocate that the $J^P$ quantum numbers of $Ξ_c(2980)$ and $Ξ_c(3077)$ are $\frac12^+$ and $\frac52^+$, respectively. Under this $J^P$ assignment, it is ready to understand why $Ξ_c(2980)$ is broader than $Ξ_c(3077)$.