Holographic modeling of nuclear matter and neutron stars

TL;DR

This paper reviews holographic models for cold nuclear matter and neutron stars, focusing on the V-QCD framework, and explores their implications for neutron star properties and gravitational wave signals.

Contribution

It introduces a hybrid approach combining effective field theory and holographic V-QCD models to study dense nuclear matter and neutron star mergers.

Findings

Hybrid equations of state can be constructed for dense matter.

Constraints on nuclear to quark matter transition are identified.

Predictions for gravitational wave spectra from neutron star mergers.

Abstract

I review holographic models for (dense and cold) nuclear matter, neutron stars, and their mergers. I start by a brief general discussion on current knowledge of cold QCD matter and neutron stars, and go on discussing various approaches to model cold nuclear and quark matter by using gauge/gravity duality, pointing out their strengths and weaknesses. Then I focus on recent results for a complex bottom-up holographic framework (V-QCD), which also takes input from lattice QCD results, effective field theory, and perturbative QCD. Dense nuclear matter is modeled in V-QCD through a homogeneous non-Abelian bulk gauge field. Feasible "hybrid" equations of state for cold nuclear (and quark) matter can be constructed by using traditional methods (e.g., effective field theory) at low densities and the holographic V-QCD model at higher densities. I discuss the constraints from this approach to the properties of the nuclear to quark matter transition as well as to properties of neutron stars. Using such hybrid equations of state as an input for numerical simulations of neutron star mergers, I also derive predictions for the spectrum of produced gravitational waves.