The half-skyrmion phase in a chiral-quark model

TL;DR

This paper explores the phase transitions in dense nuclear matter using a chiral-quark model, revealing a half-skyrmion phase and quark deconfinement at high densities, aligning with the quarkyonic matter concept.

Contribution

It introduces a detailed analysis of phase transitions in a chiral-dilaton model, highlighting the emergence of a half-skyrmion phase and the connection to quarkyonic matter.

Findings

Identification of two phase transitions: baryon delocalization and quark deconfinement.

Formation of a half-skyrmion phase at moderate densities.

Consistency with the quarkyonic phase concept.

Abstract

The Chiral Dilaton Model, where baryons arise as non-topological solitons built from the interaction of quarks and chiral mesons, shows in the high density low temperature regime a two phase scenario in the nuclear matter phase diagram. Dense soliton matter described by the Wigner-Seitz approximation generates a periodic potential in terms of the sigma and pion fields that leads to the formation of a band structure. The analysis up to three times nuclear matter density shows that soliton matter undergoes two separate phase transitions: a delocalization of the baryon number density leading to $B=1/2$ structures, as in skyrmion matter, at moderate densities, and quark deconfinement at larger densities. This description fits well into the so-called quarkyonic phase where, before deconfinement, nuclear matter should undergo structural changes involving the restoration of fundamental symmetries of QCD.