Investigation of Λ_Q and Ξ_Q baryons in the heavy quark-light diquark picture

We apply a new mass formula which is derived analytically in the relativistic flux tube model to the mass spectra of Λ_Q and Ξ_Q (Q = c or b quark) baryons. To this end, the heavy quark-light diquark picture is employed. We find that all masses of the available Λ_Q and Ξ_Q states can be understood well. The assignments to these states do not appear to contradict the strong decay properties. Λ_c(2760)⁺ and Ξ_c(2980) are assigned to the first radial excitations with J^P = 1/2⁺. Λ_c (2940)⁺ and Ξ_c(3123) might be the 2P states. The Λ_c(2880)⁺ and Ξ_c(3080) are the good 1D candidates with J^P = 5/2⁺. Λ_c(3055) is likely to be a 1D state with J^P = 3/2⁺. Λ_b (5912)⁰ and Λ_b (5920)⁰ favor the 1P assignments with J^P = 1/2^- and 3/2^-, respectively. We propose a search for the Λ_c2(5/2^-) state which can help to distinguish the diquark and three-body schemes. (orig.)