Natl Lab Heavy Ion Accelerator, Ctr Theoret Nucl Phys, Lanzhou 730000, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China
; Lab Nazl Sud, I-95123 Catania, Italy
; Univ Catania, I-95124 Catania, Italy
; Huzhou Teachers Coll, Sch Sci, Huzhou 313000, Peoples R China
; Chinese Acad Sci, Inst Theoret Phys, Beijing 100080, Peoples R China
; Beijing Univ Technol, Coll Appl Sci, Inst Theoret Phys, Beijing 100022, Peoples R China
Density dependent parametrization models of the nucleon-meson effective couplings, including the isovector scalar delta-field, are applied to asymmetric nuclear matter. The nuclear equation of state and the neutron star properties are studied in an effective Lagrangian density approach, using the relativistic mean field hadron theory. It is known that the introduction of a delta-meson in the constant coupling scheme leads to an increase of the symmetry energy at high density and so to larger neutron star masses, in a pure nucleon-lepton scheme. We use here a more microscopic density dependent model of the nucleon-meson couplings to study the properties of neutron star matter and to reexamine the delta-field effects in asymmetric nuclear matter. Our calculations show that, due to the increase of the effective delta coupling at high density, with density dependent couplings the neutron star masses in fact can be even reduced.