Unified weak/strong coupling framework for nuclear matter and neutron stars

TL;DR

This paper develops a hybrid framework combining weak and strong coupling models to describe nuclear matter and neutron stars, integrating holographic approaches with traditional nuclear physics to better match astrophysical constraints.

Contribution

It introduces a novel hybrid equation of state using holographic models for high-density matter, providing new insights into neutron star structure and stability.

Findings

Quark matter cores in neutron stars are unstable due to first-order phase transition.

The hybrid EoS satisfies astrophysical constraints and predicts neutron star radii and tidal deformabilities.

Constraints on gravitational wave frequencies from neutron star mergers are derived.

Abstract

Ab initio methods using weakly interacting nucleons give a good description of condensed nuclear matter up to densities comparable to the nuclear saturation density. At higher densities palpable strong interactions between overlapping nucleons become important; we propose that the interactions will continuously switch over to follow a holographic model in this region. In order to implement this, we construct hybrid equations of state (EoSs) where various models are used for low density nuclear matter, and the holographic V-QCD model is used for non-perturbative high density nuclear matter as well as for quark matter. We carefully examine all existing constraints from astrophysics of compact stars and discuss their implications for the hybrid EoSs. Thanks to the stiffness of the V-QCD EoS for nuclear matter, we obtain a large family of viable hybrid EoSs passing the constraints. We find that quark matter cores in neutron stars are unstable due to the strongly first order deconfinement transition, and predict bounds on the tidal deformability as well as on the radius of neutron stars. By relying on universal relations, we also constrain characteristic peak frequencies of gravitational waves produced in neutron star mergers.