Density dependencies of interaction strengths and their influences on nuclear matter and neutron stars in relativistic mean field theory

Abstract

The density dependencies of various effective interaction strengths in the relativistic mean field are studied and carefully compared for nuclear matter and neutron stars. The influences of different density dependencies are presented and discussed on mean field potentials, saturation properties for nuclear matter, equations of state, maximum masses, and corresponding radii for neutron stars. Though the interaction strengths and the potentials given by various interactions are quite different in nuclear matter, the differences of saturation properties are subtle, except for NL2 and TM2, which are mainly used for light nuclei, while the properties by various interactions for pure neutron matter are quite different. To get an equation of state for neutron matter without any ambiguity, it is necessary to constrain the effective interactions either by microscopic many-body calculations for the neutron matter data or the data of nuclei with extreme isospin. For neutron stars, the interaction with large interaction strengths give strong potentials and large Oppenheimer-Volkoff (OV) mass limits. The density-dependent interactions DD-ME1 and TW-99 favor a large neutron population due to their weak -meson field at high densities. The OV mass limits calculated from different equations of state are 2.02-2.81M ᭪ , and the corresponding radii are 10.78-13.27 km. After the inclusion of the hyperons, the corresponding values become 1.52-2.06M ᭪ and 10.24-11.38 km.

Strange quark matter and compact stars

“…In passing we mention that in recent years a new class of effective field theories was developed which treat the meson-nucleon couplings density dependent. These field theories provide a very good description of the properties of nuclear matter, atomic nuclei as well as neutron stars [55,56,57,58,59]. We conclude this section with a brief discussion of the total energy density of the system follows from the stress-energy density tensor, T µν , as [2] …”

Neutron stars and strange stars in the chiral SU(3) quark mean field model

“…(8). In the quark mean field model, quarks are confined in baryons by the Lagrangian L c = −¯ χ c [with χ c given in Eq.…”

“…Since the Walecka model [7] was proposed and applied to study the properties of nuclear matter, the relativistic mean field approach has been widely used in the determination of the masses and radii of neutron stars. These models lead to different predictions for neutron-star masses and radii [8,9]. For a recent review, see Ref.…”

Ultra-Dense Neutron Star Matter, Strange Quark Stars, and the Nuclear Equation of State

“…The most popular ones are the semi-classical ThomasFermi theory 31,32 , Schroedinger-based treatments (e.g. variational approach, Monte Carlo techniques, hole line expansion (Brueckner theory), coupled cluster method, Green function method) 4,33,34,35 , or relativistic field-theoretical treatments (relativistic mean field (RMF), Hartree-Fock (RHF), standard Brueckner-Hartree-Fock (RBHF), density dependent RBHF (DD-RBHF) 36,37,38,39,40,41 , the Nambu-JonaLasinio (NJL) model 42,43 , and the chiral SU(3) quark mean field model 44 ). An overview of EoSs computed for several of these methods is given in Fig.…”