Three-dimensional physics and the pressure of hot QCD

TL;DR

This paper refines Monte Carlo simulations of a three-dimensional SU(3) + adjoint Higgs theory to estimate infrared contributions to hot QCD pressure, revealing a smooth function that does not improve lattice data agreement.

Contribution

It provides a careful extrapolation of infrared mode contributions to hot QCD pressure, highlighting the limitations of current theoretical models.

Findings

Infrared contributions form a smooth function of reasonable magnitude.

Adding these contributions does not improve the match to four-dimensional lattice data.

Other quantities like correlation lengths and susceptibilities are well described.

Abstract

We update Monte Carlo simulations of the three-dimensional SU(3) + adjoint Higgs theory, by extrapolating carefully to the infinite volume and continuum limits, in order to estimate the contribution of the infrared modes to the pressure of hot QCD. The sum of infrared contributions beyond the known 4-loop order turns out to be a smooth function, of a reasonable magnitude and specific sign. Unfortunately, adding this function to the known 4-loop terms does not improve the match to four-dimensional lattice data, in spite of the fact that other quantities, such as correlation lengths, spatial string tension, or quark number susceptibilities, work well within the same setup. We outline possible ways to reduce the mismatch.