Universal relation between dipole polarizability of finite nuclei and neutron-star compactness

TL;DR

This paper establishes a universal relation linking the dipole polarizability of finite nuclei to neutron star compactness, enabling constraints on neutron star properties through nuclear measurements.

Contribution

It introduces a new universal relation connecting finite nuclei and neutron star properties via the dimensionless quantity ζ, reducing model dependence in neutron star studies.

Findings

Strong exponential correlation between ζ and nuclear dipole polarizability α_D.

Constraints on neutron star radius R_{1.4} derived from experimental α_D data.

Bounds on symmetry-energy slope L obtained, informing neutron star matter properties.

Abstract

The nuclear equation of state, which determines the structure and properties of neutron stars, remains subject to substantial theoretical uncertainties, leading to model dependence in predicted observables. Universal relations have emerged as a powerful tool to mitigate this dependence by linking neutron star observables in a framework-independent manner. In this work, we introduce a new universal relation that \emph{bridges} finite nuclei and neutron stars through the dimensionless quantity $\zeta = \beta_{1.4}\tilde{L}^{-1}$, which couples the compactness of a $1.4~M_{\odot}$ neutron star to the slope of the nuclear symmetry energy at saturation. The relation is examined under a broad set of relativistic energy density functionals with point-coupling and meson-exchange interactions, as well as non-relativistic Skyrme functionals. We demonstrate that $\zeta$ exhibits a strong exponential correlation with the electric dipole polarizability $\alpha_D$ in finite nuclei across all considered equations of state. By exploiting experimental $\alpha_D$ data for selected neutron-rich nuclei, we constrain $\zeta$ and translate these constraints into equation-of-state-independent bounds on the neutron star radius $R_{1.4}$ and the symmetry-energy slope $L$, providing insights into the properties of neutron star matter.