Nuclear matter properties from chiral-scale effective theory including a dilatonic scalar meson

TL;DR

This paper applies an extended chiral-scale effective theory with a dilatonic scalar meson to study nuclear matter and neutron stars, achieving improved agreement with empirical data and astrophysical constraints without extra parameters.

Contribution

It introduces a chiral-scale effective theory approach to nuclear matter, enhancing the modeling of symmetry energy and neutron star properties compared to traditional models.

Findings

Reproduces properties around nuclear saturation density accurately.

Predicts neutron star maximum mass around 3 solar masses.

Aligns neutron star structure with observational constraints.

Abstract

Chiral effective theory has become a powerful tool for studying the low-energy properties of QCD. In this work, we apply an extended chiral effective theory -- chiral-scale effective theory -- including a dilatonic scalar meson to study nuclear matter and find that the properties around saturation density can be well reproduced. Compared to the traditionally used Walecka-type models in nuclear matter studies, our approach improves the behavior of symmetry energy and the incompressibility coefficient in describing empirical data without introducing additional freedoms. Moreover, the predicted neutron star structures fall within the constraints of GW170817, PSR J0740+6620, and PSR J0030+0451, while the maximum neutron star mass can reach about $~3M_{\odot}$ with a pure hadronic phase. Additionally, we find that symmetry patterns of the effective theory significantly impact neutron star structures. %In chiral-scale effective theory, effective operators are well organized by chiral-scale orders and freedoms induced by QCD symmetry patterns. We believe that introducing this type of theory into nuclear matter studies can lead to a deeper understanding of QCD, nuclear matter, and compact astrophysical objects.