Decompactification of space or time in large N QCD_2

TL;DR

This paper solves large N QCD_2 on a cylinder, showing that non-perturbative gauge dynamics effectively decompactify space or time, with implications for confinement and phase transitions.

Contribution

It provides an exact leading order solution including zero mode gluons, revealing non-perturbative effects that decompactify the space-time dimension in large N QCD_2.

Findings

Decompactification of space or time due to gauge dynamics

No order N pressure or temperature-dependent chiral condensate

Absence of chiral and deconfining phase transitions

Abstract

QCD_2 with fundamental quarks on a cylinder is solved to leading order in the 1/N expansion, including the zero mode gluons. As a result of the non-perturbative dynamics of these gauge degrees of freedom, the compact space-time direction gets effectively decompactified. In a thermodynamic interpretation, this implies that there is no pressure of order N and that the chiral condensate of order N is temperature independent. These findings are consistent with confinement of quarks, rule out both chiral and deconfining phase transitions in the finite temperature 't Hooft model, and help to resolve some controversial issues in the literature