Effects of Phi and $\sigma^{*}$-meson on properties of hyperon stars including $\Delta$ resonance

TL;DR

This study explores how $ ho^{*}$-mesons and $ riangle$ resonances influence neutron star properties, revealing their effects on particle distributions, equations of state, and observable characteristics like mass and radius.

Contribution

It introduces a comprehensive analysis of hyperons and $ riangle$ resonances in neutron stars using RMF theory, highlighting the role of strange mesons and coupling parameters in star stability and structure.

Findings

Strange mesons appear at about 3$ ho_0$ and soften the EOS.

Increasing $x_{\sigma riangle}$ suppresses hyperons and lowers the critical density.

Including $ riangle$ resonances reduces neutron star radii, consistent with GW170817 observations.

Abstract

In this work, we study the properties of neutron stars using the linear Relativistic Mean-Field (RMF) theory and consider multiple degrees of freedom inside neutron stars, including hyperons and $\Delta$ resonances. We investigate different coupling parameters $x_{\sigma \Delta}$ between $\Delta$ resonances and nucleons and compare the differences between neutron stars with and without strange mesons $\sigma^*$ and $\phi$. These effects include particle number distributions, equations of state (EOS), mass-radius relations, and tidal deformabilities. To overcome the "hyperon puzzle," we employ the $\sigma-cut$ scheme to obtain neutron stars with masses up to $2M_{\odot}$. We find that strange mesons appear at around 3$\rho_0$ and reduce the critical density of baryons in the high-density region. With increasing coupling parameter $x_{\sigma \Delta}$, the $\Delta$ resonances suppress hyperons, leading to a shift of the critical density towards lower values. The early appearance of $\Delta$ resonances may play a crucial role in the stability of neutron stars. Strange mesons soften the EOS slightly, while $\Delta$ resonances predominantly soften the EOS in the low-density region. By calculating tidal deformabilities and comparing with astronomical observation GW170817, we find that the inclusion of $\Delta$ resonances decreases the radius of neutron stars.