ISOVECTOR COMPONENTS OF LIGHT SCALAR MESON AND NUCLEAR MATTER PROPERTIES

We have predicted (contribution to this issue) an isovector component of the light scalar meson sector by using the chiral symmetry transformation formalism. On the basis of this result, we study dense hadronic matter in a generalized relativistic mean field approach with σ, ω and ρ mesons as well as nonlinear self-couplings of the I = 1 component of a light scalar meson field and compare its predictions for neutron star properties with results from different models for nuclear matter found in the literature.

SIGNATURES OF ISOVECTOR COMPONENTS OF A LIGHT SCALAR MESON IN PULSARS

In a previous work, we have predicted an isovector component of the light scalar meson sector by using the chiral symmetry transformation formalism. On the basis of this result, we study dense hadronic matter in a generalized relativistic mean field approach with σ, ω and ρ mesons as well as nonlinear self-couplings of the I = 1 component of a light scalar meson field and compare its predictions for neutron star properties and with results from different models for nuclear matter found in the literature.

THE ROLE OF SELF-COUPLINGS OF SCALAR MESONS IN NEUTRON STAR MATTER

The influence of nonlinear cubic and quartic self-couplings of the scalar meson field in nuclear matter is investigated. In summing the leading tadpole corrections for the Dirac-vacuum, we compare two approaches, the modified relativistic Hartree approximation, applied to the Walecka model, and the relativistic Hartree approximation, employed to the nonlinear model, respectively. These two approaches render similar expressions for the equation of state of nuclear matter up to the fifth order in the scalar meson field. We find that, by exploring the parameter dependence of the two models, they yield similar results for the bulk static properties of nuclear matter. However, increasing the baryon density the two models start to deviate significantly, such as in the predictions for the maximal mass of a neutron star or in the role of hyperon degrees of freedom in dense matter. The results indicate that with increasing density, scalar meson self-couplings beyond the fourth order seem to play a significant role.

THE NAMBU-JONA-LASINIO SOLITON WITH GENERALIZED SCALAR INTERACTIONS

Soliton solutions are studied as a generalization of the bosonized Nambu-Jona-Lasinio model with a fourth order term in the scalar meson field. Such an interaction arises in the context of a scale-invariant modification of the Nambu-Jona-Lasinio action, in which the scalar meson field is coupled to a scalar glueball field. It is shown that a fourth order term in the scalar meson field is crucial for the existence of stable solitons. We investigate the dependence of soliton properties on the scalar-glueball coupling.

Some properties of Jordan-Ehlers spacetime

It is shown that for cylindrically symmetric Jordan-Ehlers spacetime, either the charged scalar meson field associated with meson rest massMor the charged perfect fluid cannot be the source for generating gravitation.

Field of a charged particle in the presence of scalar meson fields in general relativity

Field equations for coupled gravitational and zero mass scalar fields in the presence of a point charge are obtained with the aid of a static spherically symmetric conformally flat metric. A closed from exact solution of the field equations is presented which may be considered as describing the field of a charged particle at the origin surrounded by the scalar meson field in a flat space-time.