Hyperon-mixed neutron star with universal many-body repulsion

Neutron stars with large masses \( \sim 2M_{\odot}\) require the hard stiffness of equation of state (EoS) of neutron-star matter. On the other hand, hyperon mixing brings about remarkable softening of EoS. In order to solve this problem, a multi-pomeron exchange potential (MPP) is introduced as a model for the universal many-body repulsion in baryonic systems on the basis of the Extended Soft Core (ESC) baryon-baryon interaction. The strength of MPP is determined by analyzing the nucleus-nucleus scattering with the G -matrix folding model. The interactions in \( \Lambda N\) , \( \Sigma N\) and \( \Xi N\) channels are shown to be consistent with experimental indications. The EoS in neutron-star matter with hyperon mixing is obtained from ESC in addition of MPP, and mass-radius relations of neutron stars are derived. The maximum mass is shown to reach \( 2M_{\odot}\) even in the case of including hyperon mixing on the basis of model-parameters determined by terrestrial experiments.