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

Ting-Ting Sun, Cheng-Jun Xia, Shi-Sheng Zhang, M. S. Smith

Published 2017-12-15Version 1

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.