Viscosity Correlators in Improved Holographic QCD

TL;DR

This paper uses a bottom-up holographic model to study spectral densities in large-Nc Yang-Mills theory, analyzing how conformal invariance breaking affects shear and bulk channels at finite temperature.

Contribution

It introduces a holographic model with a dilaton potential to explore spectral functions and compare results across different theoretical frameworks and lattice QCD.

Findings

Spectral densities in shear channel match strongly coupled N=4 SYM and weakly coupled Yang-Mills.

Bulk channel results align with perturbative and lattice QCD data.

Conformal invariance breaking significantly influences spectral functions.

Abstract

We study a bottom-up holographic model of large-Nc Yang-Mills theory, in which conformal invariance is broken through the introduction of a dilaton potential on the gravity side. We use the model to calculate the spectral densities of the shear and bulk channels at finite temperature. In the shear channel, we compare our results to those derived in strongly coupled N=4 Super Yang-Mills theory as well as in weakly coupled ordinary Yang-Mills. In the bulk channel, where the conformal result is trivial, we make comparisons with both perturbative and lattice QCD. In both channels, we pay particular attention into the effects of conformal invariance breaking in the IHQCD model.