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

Abstract

We apply a new mass formula which is derived analytically in the relativistic flux tube model to the mass spectra of $Λ_Q$ and $Ξ_Q$ (\emph{Q} = \emph{c} or \emph{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 2\emph{P} states. The $Λ_c(2880)^+$ and $Ξ_c(3080)$ are the good 1\emph{D} candidates with $J^P = 5/2^+$. $Ξ_c(3055)$ is likely to be a 1\emph{D} state with $J^P = 3/2^+$. $Λ_b(5912)^0$ and $Λ_b(5920)^0$ favor the 1\emph{P} assignments with $J^P = 1/2^-$ and $3/2^-$, respectively. We propose a search for the $\tildeΛ_{c2}(5/2^-)$ state which can help to distinguish the diquark and three-body schemes.

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