Excitation spectra of heavy baryons in diquark models

TL;DR

This paper investigates the excitation spectra of heavy baryons using diquark models, comparing point-like and spatially extended diquarks to understand their role as constituents in heavy baryons.

Contribution

It introduces and compares two diquark models with different spatial assumptions, analyzing their ability to reproduce heavy baryon excitation spectra.

Findings

Model A reproduces excitation spectra well

Model B predicts degeneracy not observed experimentally

String tension in Model A is half that of charmonium

Abstract

The excitation energy spectra of heavy baryons consisting of a heavy quark and two light quarks are investigated by using diquark models in order to examine the nature of the diquark as a constituent of single heavy baryons. We consider two diquark models; in model A the diquark is treated as a point-like particle, while it has a spatial size in model B. We determine the masses of scalar and axial vector diquarks by the mass difference of the ground state charmed baryons to the $\Lambda_{c}$ baryon, while the mass of the $ud$ scalar diquark in the $\Lambda_{c}$ baryon is assumed to be 500 MeV as a reference. The parameters of these models are fixed by the $1p$ excitation energy of $\Lambda_{c}$. We find that model A reproduces well the excitation energy spectra of the charmed and bottomed baryons, although the string tension of the confinement potential in model A should be a half of that of the charmonium, while Model B suggests degeneracy of the $2s$ and $1d$ states, which is not seen in the $\Lambda_{c}$ spectrum.