Thermodynamics of SU(N) Yang-Mills theories in 2+1 dimensions I - The confining phase

TL;DR

This paper investigates the thermodynamics of SU(N) Yang-Mills theories in 2+1 dimensions, showing that a glueball gas model explains low-temperature behavior, but heavier states near deconfinement require a string-inspired spectral density.

Contribution

It provides lattice simulation results for multiple SU(N) groups and introduces a string model to describe the spectral density of heavier glueballs near deconfinement.

Findings

Glueball gas accurately describes low-temperature thermodynamics.

Heavier glueballs are essential near the deconfinement temperature.

String model effectively captures the spectral density of heavy states.

Abstract

We compute the equation of state in the confining phase of SU(N) Yang-Mills theories with N=2, 3, 4, 5 and 6 colors in 2+1 dimensions, via lattice simulations. At low enough temperatures, the results are accurately described by a gas of glueballs, including all known states below the two-particle threshold. Close to the deconfinement temperature, however, this prediction underestimates the numerical results, and the contribution from heavier glueballs has to be included. We show that the spectral density of the latter can be accurately described using a simple bosonic string model.