Low-lying doubly heavy baryons: Regge relation and mass scaling

TL;DR

This paper develops a theoretical framework combining Regge trajectories and mass scaling to predict the masses of low-lying doubly heavy baryons, providing insights into their excitation spectra and heavy diquark dynamics.

Contribution

It introduces a novel semi-classical approach using Regge relations and heavy diquark symmetry to estimate excited baryon masses, extending previous models with new mass scaling techniques.

Findings

Level spacings of heavy diquark excitations are smaller than light-quark excitations.

Predicted masses of excited doubly heavy baryons up to 2S and 1P states.

The approach aligns with observed data for the doubly charmed baryon c.

Abstract

In framework of heavy-diquark$-$light-quark endowed with heavy-pair binding, we explore excited baryons $QQ^{\prime}q$ containing two heavy quarks ($QQ^{\prime}=cc,bb,bc$) by combining the method of Regge trajectory with the perturbative correction due to the heavy-pair interaction in baryons. Two Regge relations, one linear and the other nonlinear, are constructed semi-classically in the QCD string picture, and a mass scaling relation based on the heavy diquark-heavy antiquark symmetry are employed between the doubly heavy baryons and heavy mesons. We employ the ground-state mass estimates compatible with the observed doubly charmed baryon $\Xi_{cc}$ and spectra of the heavy quarkonia to determine the trajectory parameters and the binding energies of the heavy pair, and thereby compute the low-lying masses of the excited baryons $\Xi_{QQ^{\prime}}$ and $\Omega_{QQ^{\prime}}$ up to 2S and 1P excitations of the light quark and heavy diquark. The level spacings of heavy diquark excitations are found to be smaller generally than that of the light-quark excitations, in according with the nature of adiabatic expansion between the heavy and light-quark dynamics.