NJL-Chiral Soliton and the Nucleon Equation of State at supra-saturation density: Impact of Chiral Symmetry Restoration

TL;DR

This paper models nucleons as topological solitons within an NJL framework to derive the equation of state at high densities, showing chiral symmetry restoration stiffens the EoS compatible with neutron star data.

Contribution

It introduces a soliton-based approach to connect nucleon structure with the high-density nuclear matter EoS, incorporating chiral symmetry restoration dynamically.

Findings

Chiral symmetry restoration stiffens the nucleon-based EoS.

The model aligns with neutron star EoS constraints.

Nucleon properties vary with NJL parameters and density.

Abstract

It has been conjectured that, at sufficiently high baryon densities, the equation of state (EoS) of bulk nuclear matter can be identified with that of the nucleon core. In this work, we illustrate how the energy density and pressure distributions inside individual nucleons can be utilized to construct the EoS of supra-dense matter. In our framework, nucleons arise as topological solitons stabilized by vector mesons, which are dynamically generated through the path integral bosonization of an underlying Nambu-Jona-Lasinio (NJL) model. The restoration of chiral symmetry is implemented dynamically via a self-consistent, density-dependent scalar field, which modifies the (isovector) and (isoscalar) channels of the soliton. We analyze the resulting changes in soliton properties for different NJL parameter sets and demonstrate that the progressive restoration of chiral symmetry leads to a stiffening of the soliton-based EoS, making it compatible with existing neutron star EoSs. An EoS constructed from the solutions of the energy-density and pressure profiles at the center of the nucleon is also explored.