Making a soft relativistic mean-field equation of state stiffer at high density

Understand

We study relativistic mean-field (RMF) models including nucleons interacting with scalar, vector and iso-vector mean fields and self- and cross- mean-field interaction terms.

• Usually, in such a models the magnitude of the scalar field increases monotonically with the nucleon density, and the nucleon effective mass decreases.
• We demonstrate that the latter quantity stops to decrease and the equation of state stiffens, provided the mean-field self-interaction potential rises sharply in a narrow vicinity of the values of mean fields corresponding to nucleon densities $n> n_{*}>n_0$, where $n_0$ is the nuclear saturation density.
• As the result the limiting neutron star mass increases.