Many-body forces in the equation of state of hyperonic matter

TL;DR

This paper extends a theoretical model to include many-body forces in hyperonic matter, constraining parameters with nuclear data, and demonstrates the model's consistency with experimental data and its implications for massive hyperon stars.

Contribution

It introduces an extended formalism incorporating many-body forces via non-linear couplings, improving the description of hyperonic matter and neutron star properties.

Findings

Model agrees with experimental data on hyperonic matter.

Allows for hyperon stars exceeding 2 solar masses.

Predicts small radii for massive hyperon stars.

Abstract

In this work we introduce an extended version of the formalism proposed originally by Taurines et al. that considers the effects of many-body forces simulated by non-linear self-couplings and meson-meson interaction contributions. In this extended version of the model, we assume that matter is at zero temperature, charge neutral and in beta-equilibrium, considering that the baryon octet interacts by the exchange of scalar-isoscalar ($\sigma$,$\,\sigma^*$), vector-isoscalar ($\omega$,$\,\phi$), vector-isovector ($\varrho$) and scalar-isovector ($\delta$) meson fields. Using nuclear matter properties, we constrain the parameters of the model that describe the intensity of the indirectly density dependent baryon-meson couplings to a small range of possible values. We then investigate asymmetric hyperonic matter properties. We report that the formalism developed in this work is in agreement with experimental data and also allows for the existence of massive hyperon stars (with more than $2M_{\odot}$) with small radii, compatible with astrophysical observations.