Effects of $\omega$ meson self-coupling on the properties of finite nuclei and neutron stars

The effects of $\omega$ meson self-coupling (OMSC) on the properties of finite nuclei and neutron stars are investigated within the framework of effective field theory based relativistic mean-field (ERMF) model which includes the contributions from all possible mixed interactions between the scalar-isoscalar ($\sigma$), vector-isoscalar ($\omega$) and vector-isovector ($\rho$) mesons upto the quartic order. For a realistic investigation, several parameter sets corresponding to different values of OMSC are generated by adjusting the remaining parameters of the ERMF model to fit the properties of the finite nuclei. Though, all these parameter sets give equally good fit to the properties of the finite nuclei, only moderate values of OMSC are favored from the "naturalness" point of view. The equation of state for the symmetric nuclear and pure neutron matters resulting from the parameter sets with the moderate values of OMSC are in close agreement with the ones obtained within the Dirac-Brueckner-Hartree-Fock approximation. For such parameter sets the limiting mass for the neutron stars composed of $\beta$-stable matter is $\sim 1.9M_\odot$. It is found that the direct Urca process can occur in the neutron stars with "canonical" mass of $1.4M_\odot$ only for the moderate and higher values of OMSC. Some other interesting properties for the neutron stars are also discussed.

Raj Kumar, B. K. Agrawal, Shashi K. Dhiman · 2006