Massive neutron stars and $\Lambda$-hypernuclei in relativistic mean field models

TL;DR

This study uses relativistic mean field models to analyze hypernuclei and massive neutron stars, showing that hyperon interactions can explain observed neutron star masses without extra particles.

Contribution

It demonstrates that hyperon-meson couplings consistent with hypernuclear data can account for massive neutron stars, resolving the Hyperon Puzzle within RMF models.

Findings

Hyperon-meson couplings follow a simple relation.

Massive neutron stars can be explained without extra degrees of freedom.

The model reproduces hypernuclear binding energies and neutron star masses.

Abstract

Based on relativistic mean field (RMF) models, we study finite $\Lambda$-hypernuclei and massive neutron stars. The effective $N$-$N$ interactions PK1 and TM1 are adopted, while the $N$-$\Lambda$ interactions are constrained by reproducing the binding energy of $\Lambda$-hyperon at $1s$ orbit of $^{40}_{\Lambda}$Ca. It is found that the $\Lambda$-meson couplings follow a simple relation, indicating a fixed $\Lambda$ potential well for symmetric nuclear matter at saturation densities, i.e., around $V_{\Lambda} = -29.786$ MeV. With those interactions, a large mass range of $\Lambda$-hypernuclei can be well described. Furthermore, the masses of PSR J1614-2230 and PSR J0348+0432 can be attained adopting the $\Lambda$-meson couplings $g_{\sigma\Lambda}/g_{\sigma N}\gtrsim 0.73$, $g_{\omega\Lambda}/g_{\omega N}\gtrsim 0.80$ for PK1 and $g_{\sigma\Lambda}/g_{\sigma N}\gtrsim 0.81$, $g_{\omega\Lambda}/g_{\omega N}\gtrsim 0.90$ for TM1, respectively. This resolves the Hyperon Puzzle without introducing any additional degrees of freedom.