Heavy-quark dominance and fine structure of excited heavy baryons $\Sigma_{Q}$, $\Xi '_{Q}$ and $\Omega_{Q}$

TL;DR

This paper improves the relativized quark model to analyze the fine structures of excited heavy baryons, revealing violations of heavy quark dominance in certain states and aiding in the precise classification of observed baryons.

Contribution

It introduces an improved calculation of spin-orbit interactions considering light quark clusters, leading to better understanding of heavy baryon structures and violations of heavy quark dominance.

Findings

Significant modification of energy level splitting due to light quark contributions.

Violation of heavy quark dominance in 1P-wave states of certain baryons.

Accurate assignment of observed heavy baryons based on predicted fine structures.

Abstract

In the framework of the relativized quark model, the calculation of spin-orbit interactions is improved by considering the contribution from the light quark cluster in a singly heavy baryon. It modifies the energy level splitting of the orbital excitation significantly and causes the emergence of fine structures for $\Sigma_{Q}$, $\Xi '_{Q}$ and $\Omega_{Q}$ baryons. Based on this improvement, we systematically analyze the fine structures and retest the heavy quark dominance mechanism. This mechanism is found to be violated in the $1P$-wave states of the $\Sigma_{c}$, $\Xi '_{c}$ and $\Omega_{c}$ baryons although it remains effective overall, which may help to understand the nature of the heavy quarks and strong interactions. With the predicted fine structures, we make the precise assignments of those observed heavy baryons which once could not be accurately explained due to their close mass values. The method used in this work is instructive and applicable for the study of more complex exotic hadrons, such as the heavy tetraquarks and pentaquarks.