Quark-Antiquark Bound States in an Extended QCD_2 Model

TL;DR

This paper investigates a 2D extended QCD model derived from 4D QCD, revealing dynamical mass generation for gluons and chiral symmetry breaking, and analyzing quark-antiquark bound states with properties reflecting the original 4D Lorentz symmetry.

Contribution

It introduces an extended 2D QCD model from 4D QCD, demonstrating dynamical gluon mass, chiral symmetry breaking, and classifying bound states by 4D Lorentz properties.

Findings

Dynamical mass generation for transverse gluons

Chiral symmetry breaking with non-tachyonic quark masses

Classification of bound states by Lorentz transformations

Abstract

We study an extended QCD model in 2D obtained from QCD in 4D by compactifying two spatial dimensions and projecting onto the zero-mode subspace. This system is found to induce a dynamical mass for transverse gluons -- adjoint scalars in QCD(2), and to undergo a chiral symmetry breaking with the full quark propagators yielding non-tachyonic, dynamical quark masses, even in the chiral limit. We construct the hadronic color singlet bound-state scattering amplitudes and study quark-antiquark bound states which can be classified in this model by their properties under Lorentz transformations inherited from 4D.