Evolution of strangeness and hyperons in quarkyonic matter

TL;DR

This paper investigates how quark saturation influences the emergence of hyperons in dense matter, revealing delayed hyperon formation and implications for neutron star equations of state.

Contribution

It extends the ideal Quarkyonic matter model to include strangeness, providing new insights into hyperon onset and quark saturation effects in dense baryonic matter.

Findings

D-quark saturation occurs before hyperons appear.

Hyperon onset density is delayed to 5-6 times nuclear saturation density.

Quark saturation mitigates the hyperon puzzle in neutron stars.

Abstract

We study the evolution of matter composition from nuclear to quark densities in the confining regime, by extending an ideal model of Quarkyonic matter, IdylliQ model, to multi-flavor systems including strangeness. The model provides a dual description of quark and baryon occupation probabilities which are determined by minimizing the energy of the system. Saturation of low-momentum quark states drives the formation of quark matter and constrains baryon distributions, inducing statistical repulsion among baryon species. Applying the model to charge-neutral matter composed of neutrons, $\Lambda_0$, and $\Sigma_0$ hyperons, we find that, for typical size of baryons, $d$-quark saturation occurs before hyperons appear, delaying their onset and shifting the threshold density from $\sim 2$--$3n_{\rm sat}$ to $\sim 5$--$6n_{\rm sat}$ ($n_{\rm sat} \approx 0.16\,{\rm fm^{-3}}$: nuclear saturation density). After hyperons emerge, low-momentum hyperon states remain only sparsely occupied due to the quark saturation. These features mitigate the hyperon puzzle, in which the appearance of hyperons softens neutron star equations of state significantly by increasing energy density with little pressure increase. Our results highlight the key role of quark saturation in dense baryonic matter and provide new insights into the interplay between quark dynamics and hyperon physics in neutron stars.