Implications of isoscalar and isovector scalar meson mixed interaction on nuclear and neutron star properties

The properties of finite nuclei, bulk nuclear matter, and neutron stars are studied using the relativistic mean field model which includes nonlinear couplings between isoscalar and isovector mesons. The quartic interaction σ²δ² due to isoscalar and isovector scalar, σ and δ mesons, is also taken into account in addition to vector meson mixing ω²ρ² . Several HPNL sets (named from Himachal Pradesh University Nuclear Laboratory) are generated to assess the influence of isoscalar and isovector scalar meson mixed interactions σ²δ² on the density dependence of symmetry energy and neutron star properties. These parametrizations correspond to different values of coupling constant, Λ_{σ δ} of σ -δ meson mixing and are obtained by fitting the available experimental data of ground state properties (binding energies and charge radii) for finite nuclei, infinite nuclear matter, and observed maximum mass of PSR J0740 +6620 by following the χ² minimization procedure. Furthermore, the σ -δ mixing is found to have a large influence on the radius and tidal deformability of a canonical neutron star. These new relativistic interactions are found to be simultaneously compatible with the constraints on the equation of state of symmetric nuclear and pure neutron matter from particle flow data in heavy ion collisions, the neutron skin thickness of ²⁰⁸Pb from PREX-II results, the mass-radius relations measured from NICER, and the limits of dimensionless tidal deformability of a canonical neutron star from binary neutron star merger GW170817 and GW190814 events.