Bulk and shear spectral functions in weakly and strongly coupled Yang-Mills theory

TL;DR

This paper reviews recent calculations of spectral functions related to the energy momentum tensor in high-temperature SU(N) Yang-Mills theory, using both weak coupling and holographic methods to compare different theoretical approaches.

Contribution

It provides a comprehensive comparison of spectral functions obtained via perturbative and holographic techniques, aiding nonperturbative lattice extractions of viscosities.

Findings

Spectral functions computed using gauge/gravity duality and perturbation theory.

Comparison of Euclidean correlators across different methods.

Insights into the limits of weak and strong coupling approaches.

Abstract

In this talk, we discuss a number of recent calculations aimed at determining the spectral functions corresponding to various components of the energy momentum tensor in high-temperature SU(N) Yang-Mills theory. The computations reviewed include applications of both weak coupling and gauge/gravity techniques, and thus enable one to access different limits of the quantities. The motivation for the work is twofold: On one hand, the results are hoped to aid the eventual nonperturbative extraction of the bulk and shear viscosities from lattice data, while on the other hand they also enable an immediate comparison of the lattice, perturbative and holographic predictions for certain Euclidean correlators.