# Scale-Invariant Hidden Local Symmetry, Topology Change and Dense Baryonic Matter II

## TL;DR

This paper uses topological and symmetry-based models to predict the equation of state for dense baryonic matter, aligning with nuclear properties and supporting massive neutron stars, while revealing novel symmetry phenomena at high densities.

## Contribution

It introduces a scale-invariant hidden local symmetry approach with topological inputs to model dense matter, highlighting parity doubling and emergent symmetries at high density.

## Key findings

- Equation of state consistent with nuclear matter properties
- Supports maximum neutron star mass of ~2 solar masses
- Sound velocity approaches conformal limit at high densities

## Abstract

Exploiting certain robust topological inputs from the skyrmion description of compressed baryonic matter with a scale-chiral symmetric Lagrangian, we predict the equation of state that is consistent with the properties of nuclear matter at the equilibrium density, supports the maximum mass of massive compact star $\sim 2 M_\odot$ and surprisingly gives the sound velocity close to the "conformal velocity" $1/\sqrt{3}$ at densities $\gtrsim 3 n_0$. At the core of this result is the observation that parity-doubling occurs in the nucleon structure as density goes above $\sim 2n_0$ with a chiral-singlet mass $m_0 \sim (0.6-0.9) m_N$, hinting at a possible up-to-date unsuspected source of proton mass and an emergence at high density of scale symmetry and flavor local symmetry, both hidden in the QCD vacuum.