Leptophilic Interactions in Nuclear Energy Density Functional Theory

TL;DR

This paper introduces a new extension to nuclear energy density functional theory that incorporates leptophilic interactions, affecting nuclear properties and dense matter characteristics, and enabling nuclear systems to probe new leptonic physics.

Contribution

The paper develops a unified, self-consistent framework embedding leptophilic vector bosons into nuclear EDFs, linking new physics with observable nuclear and dense matter properties.

Findings

Percent-level changes in proton fraction and symmetry energy in dense matter.

Neutron-skin thickness shifts of 10^{-3} to 10^{-2} fm in finite nuclei.

Leptophilic interactions produce detectable effects in nuclear structure and dense matter.

Abstract

We develop a unified theoretical framework that embeds a light leptophilic vector boson into nuclear energy density functional (EDF) theory. Starting from an underlying leptophilic gauge interaction, the mediator is integrated out in the static limit, yielding an effective current--current interaction that couples proton and lepton densities. This interaction is incorporated self-consistently into relativistic mean-field equations, defining a leptophilic extension of conventional nuclear EDFs. The resulting leptophilic EDF induces correlated modifications of proton and lepton chemical potentials, directly affecting beta equilibrium in dense matter. In uniform matter, these effects lead to percent-level changes in the proton fraction, symmetry energy, and equation of state within phenomenologically allowed parameter ranges. In finite nuclei, the modified proton mean field generates shifts of $10^{-3}$--$10^{-2}\,\mathrm{fm}$ in neutron-skin thicknesses, comparable to current experimental sensitivities. Our results demonstrate that light leptophilic interactions leave coherent and experimentally accessible imprints on both nuclear structure and dense-matter observables. The framework introduced here provides a controlled and realistic extension of nuclear EDF theory, enabling nuclear systems to serve as laboratories for probing new physics in the leptonic sector.