Glueball spectrum in a (1+1)-dimensional model for QCD

TL;DR

This paper investigates the spectrum of glueballs in a simplified (1+1)-dimensional QCD model derived from higher dimensions, revealing a discrete, exponentially growing spectrum with some states well approximated by parton number eigenstates.

Contribution

It provides a numerical analysis of the glueball spectrum in a (1+1)-dimensional QCD model, highlighting the spectral properties and the accuracy of truncated diagonalizations for low-lying states.

Findings

Discrete spectrum of glueballs with exponential level density

Low-lying states closely approximate parton eigenstates

Masses of some states can be accurately computed using truncated diagonalizations

Abstract

We consider (1+1)-dimensional QCD coupled to scalars in the adjoint representation of the gauge group SU($N$). This model results from dimensional reduction of the (2+1)-dimensional pure glue theory. In the large-N limit we study the spectrum of glueballs numerically, using the discretized \lcq. We find a discrete spectrum of bound states, with the density of levels growing approximately exponentially with the mass. A few low-lying states are very close to being eigenstates of the parton number, and their masses can be accurately calculated by truncated diagonalizations.