Eduardo Lütz

EFFECTIVE MESONIC AND BARYONIC DEGREES OF FREEDOM IN NEUTRON STARS

We present a sketchy survey on the role of effective mesonic and baryonic degrees of freedom in dense hadronic matter and briefly mention still very crude attempts to include constituent quarks degrees of freedom for a transition to a quark gluon plasma.

ISOVECTOR COMPONENTS OF THE SCALAR σ-MESON FAMILY AS NEW INGREDIENTS FOR NUCLEAR MATTER MODELS

On the basis of a chiral symmetry transformation, we predict an isovector component for the family of light scalar mesons, i.e. partners of the σ-meson. Such a contribution may be necessary to tune the equation of state of nuclear matter in order to comply with severe constraints from a recent analysis of observational macroscopic properties of neutron stars.

SIGNATURES OF ISOVECTOR COMPONENTS OF THE SCALAR σ-MESON IN NEUTRON STARS

Based on non-crossed, crossed and correlated ππ exchanges with irreducible N, Δ intermediate states, we predict an isovector component for the σ meson. We study dense hadronic matter in a generalized relativistic mean field approach with nonlinear self-couplings of the I=0,1 components of the scalar field and compare its predictions for neutron star properties with results from different models 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.

NÄIVE DIMENSIONAL ANALYSIS IN AN EFFECTIVE FIELD THEORY FOR NEUTRON STARS

In the investigation of the role of naturalness in effective theory, we focus on dense hadronic matter in a generalized relativistic multi-baryon Lagrangian density mean field approach which contains nonlinear self-couplings of the σ and δ meson fields interacting with the fundamental baryon octet and with the ω and ϱ meson fields and compare its predictions with estimates obtained within a phenomenological naive dimensional analysis based on the naturalness of the coupling constants of the Lagrangian model; our investigation is limited however to the scalar sector of the theory. Upon adjusting the model parameters to describe bulk static properties of ordinary nuclear matter, we show that our approach represents a natural modelling of nuclear matter under the extreme conditions of density as found in the interior of neutron stars.

The role of isospin components of the scalar [sigma]-meson in the structure of neutron stars

Based on non‐crossed, crossed and correlated ππ exchanges with irreducible N,Δ intermediate states, we predict an isovector component for the δ meson. We study dense hadronic matter in a generalized relativistic mean field approach with nonlinear self‐couplings of the I = 0, 1 components of the scalar field and compare its predictions for neutron star properties with results from different models found in the literature.

Front Form Approach to qQ̄ Mesons with Harmonic Confinement

We investigate mesons as unequal mass qQ objects in the front form representation (equivalently, on the light cone (LC) or in the infinite momentum frame (IMF)). Our starting point is the manifestly covariant Bethe‐Salpeter equation (BS) in the instant form, which we reduce to a 3‐dimensional covariant LC equation by restricting the quark and sea antiquark system symmetrically off their mass shells. We discuss analytical solutions to the LC amplitude and compare our findings with current parameterizations of the distribution amplitude emphasizing the characteristic x‐dependence for unequal quark masses.