Chiral symmetries in nuclear physics

In this report the theoretical concepts of a chirally symmetric meson field theory are reviewed and an overview of the most relevant applications in nuclear physics is given. This includes a unified description of the vacuum properties of hadrons, finite nuclei and hot, dense and strange nuclear matter in an extended chiral SU(3)_L x SU(3)_R σ-ω model.

Absence of binding in the Nelson and piezoelectric polaron models

In the context of the massless Nelson model, we prove that two non-relativistic nucleons interacting with a massless meson field do not bind when a sufficiently strong Coulomb repulsion between the nucleons is added to the Hamiltonian. The result holds for both the renormalized and unrenormalized theories, and can also be applied to the so-called piezoelectric polaron model, which describes an electron interacting with the acoustical vibrational modes of a crystal through the piezoelectric interaction. The result can then be interpreted as well as a no-binding statement about piezoelectric bipolarons. The methods used allow also for a significant reduction of about 30% over previously known no-binding conditions for the optical bipolaron model of H. Fröhlich.

EXTENSION OF THE PERIODIC SYSTEM: SUPERHEAVY, SUPERSTRANGE, ANTIMATTER NUCLEI

The extension of the periodic system into various new areas is investigated. Experiments for the synthesis of superheavy elements and the predictions of magic numbers are reviewed. Further on, investigations on hypernuclei and the possible production of antimatter-clusters in heavy-ion collisions are reported. Various versions of the meson field theory serve as effective field theories at the basis of modern nuclear structure and suggest structure in the vacuum which might be important for the production of hyper- and antimatter.

δ MESON EFFECTS ON NEUTRON STARS IN THE MODIFIED QUARK–MESON COUPLING MODEL

The properties of neutron stars are investigated by including δ meson field in the modified quark–meson coupling model. It is found that δ meson has opposite effects on hadronic matter with or without hyperons: it softens the EOSs of hadronic matter with hyperons, while it stiffens the EOSs of pure nucleonic matter. Moreover, by replacing the isovector mesons with the contact scalar–isovector interaction, a considerable change of proton fraction is observed. It is shown that the contact scalar–isovector interaction provides an approach to satisfy the constraint of Direct Urca critical star masses. However, the inclusion of δ meson increases the proton fraction, consequently it decreases the M DU which departs farther from the Direct Urca constraint. Furthermore, the inclusion of δ meson field can increase the maximum mass of neutron star and enlarge the corresponding radius, while these quantities are decreased when the contact scalar–isovector interaction is included.

DECONFINEMENT PHASE TRANSITION IN NEUTRON STARS AND δ-MESON FIELD IN RMF THEORY

The Maxwell and Glendenning construction scenarios of deconfinement phase transition in neutron star matter are investigated. The hadronic phase is described within the relativistic mean-field (RMF) theory, if the scalar-isovector δ-meson field is also taken into account. The strange quark phase is described in the frame of MIT bag model, including the effect of perturbative one-gluon exchange interactions. The influence of the δ-meson field on the deconfinement phase transition boundary characteristics is discussed.

META-STABLE BRANE CONFIGURATIONS BY DUALIZING THE TWO GAUGE GROUPS

We consider the [Formula: see text] supersymmetric gauge theories with product gauge groups. The two kinds of D6-branes in the electric theory are both displaced and rotated respectively where these deformations are interpreted as the mass terms and quartic terms for the two kinds of flavors. Then we apply the Seiberg dual to the whole gauge group factors by moving the branes and obtain the corresponding dual gauge theories. By analyzing the magnetic superpotentials consisting of an interaction term between a magnetic meson field and dual matters as well as the above deformations for each gauge group, we present the type IIA nonsupersymmetric meta-stable brane configurations.