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

Abstract

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