Assignments of ${\Lambda }_Q$ and ${\Xi }_Q$ 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 ${\Lambda }_Q$ and ${\Xi }_Q$ (\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 ${\Lambda }_Q$ and ${\Xi }_Q$ states can be understood well. The assignments to these states do not appear to contradict the strong decay properties. ${\Lambda }_c(2760{)}^{+}$ and ${\Xi }_c(2980)$ are assigned to the first radial excitations with $J^P=1/2^{+}$. ${\Lambda }_c(2940{)}^{+}$ and ${\Xi }_c(3123)$ might be the 2\emph{P} states. The ${\Lambda }_c(2880{)}^{+}$ and ${\Xi }_c(3080)$ are the good 1\emph{D} candidates with $J^P=5/2^{+}$. ${\Xi }_c(3055)$ is likely to be a 1\emph{D} state with $J^P=3/2^{+}$. ${\Lambda }_b(5912{)}^0$ and ${\Lambda }_b(5920{)}^0$ favor the 1\emph{P} assignments with $J^P=1/2^{-}$ and $3/2^{-}$, respectively. We propose a search for the ${\tilde{\Lambda }}_{c2}(5/2^{-})$ state which can help to distinguish the diquark and three-body schemes.

Comments: 9 tables, more discussions and references added