On a possibility of exotic heavy baryons

TL;DR

This paper interprets recent LHCb observations of excited $\,Omega_c^0$ baryons using the Chiral Quark Soliton Model, proposing some as parity excitations and others as exotic pentaquarks, and extends the model to heavy baryons.

Contribution

It introduces a novel interpretation of LHCb $\,Omega_c^0$ resonances within the Chiral Quark Soliton Model, including exotic pentaquark states, and generalizes the model to heavy baryons.

Findings

Three resonances are parity excitations of ground state sextets.

Two narrow resonances are exotic pentaquarks in the $\,ar{15}$ representation.

The model successfully describes known heavy baryon excitations.

Abstract

Triggered by a recent announcement by the LHCb Collaboration of five excited $\Omega^0_c$ resonances of small widths we propose an interpretation based on the Chiral Quark Soliton Model. We argue that three of the LHCb resonances are parity ($-$) excitations of the ground state SU(3) sextets, while the other two with the smallest widths are exotic pentaquarks that belong to the SU(3) $\overline{\mathbf{15}}$. We first briefly review the model and discuss the status of the putative $\Theta^+(1540)$. Next we show how to generalize the model to the case of heavy baryons. We test this approach against the ground state $\overline{\mathbf{3}}$ and ${\mathbf{6}}$ heavy baryons, and discuss different excitations that are possible in the Chiral Quark Soliton Model. We show that the model accommodates two excited $\overline{\mathbf{3}}$ in the charm sector that are experimentally observed. Finally we discuss possible assignments of the LHCb $\Omega^0_c$ states.