Holographic approach to transport in dense QCD matter

The transport properties of dense QCD matter play a crucial role in the physics of neutron stars and their mergers but are notoriously difficult to study with traditional quantum field theory tools. Specializing to the case of unpaired quark matter in beta equilibrium, we approach the problem through the machinery of holography, in particular the V-QCD and D3-D7 models, and derive results for the electrical and thermal conductivities and the shear and bulk viscosities. In addition we compare the bulk to shear viscosity ratio to the speed of sound and find that it violates the so-called Buchel bound. Our results differ dramatically from earlier predictions of perturbative QCD, the root causes and implications of which we analyze in detail.

Automated summary

The transport properties of dense QCD matter, important in the physics of neutron stars and their mergers, are difficult to study using traditional quantum field theory tools. This study focuses on unpaired quark matter in beta equilibrium and uses holography, specifically the V-QCD and D3-D7 models, to derive results for electrical and thermal conductivities, as well as shear and bulk viscosities. Comparisons show deviations from perturbative QCD predictions, which are analyzed in detail.