300 research outputs found
Hadrons in Dense Resonance-Matter: A Chiral SU(3) Approach
A nonlinear chiral SU(3) approach including the spin 3/2 decuplet is
developed to describe dense matter. The coupling constants of the baryon
resonances to the scalar mesons are determined from the decuplet vacuum masses
and SU(3) symmetry relations. Different methods of mass generation show
significant differences in the properties of the spin-3/2 particles and in the
nuclear equation of state.Comment: 28 pages, 9 figure
Neutron halos in heavy nuclei -- relativistic mean field approach
Assuming a~simple spherical relativistic mean field model of the nucleus, we
estimate the width of the antiproton--neutron annihilation () and the
width of antiproton--proton () annihilation, in an antiprotonic atom
system. This allows us to determine the halo factor , which is then
discussed in the context of experimental data obtained in measurements recently
done on LEAR utility at CERN. Another quantity which characterizes the
deviation of the average nuclear densities ratio from the corresponding ratio
of the homogeneous densities is introduced too. It was shown that it is also a
good indicator of the neutron halo. The results are compared to experimental
data as well as to the data of the simple liquid droplet model of the nuclear
densities. The single particle structure of the nuclear density tail is
discusssed also.Comment: revtex, 12 pages + 6 postscript figure
The surface diffuseness and the spin-orbital splitting in relativistic continuum Hartree-Bogoliubov theory
The Relativistic Continuum Hartree Bogoliubov theory (RCHB), which is the
extension of the Relativistic Mean Field and the Bogoliubov transformation in
the coordinate representation, has been used to study tin isotopes. The pairing
correlation is taken into account by a density-dependent force of zero range.
RCHB is used to describe the even-even tin isotopes all the way from the proton
drip line to the neutron drip line. The contribution of the continuum which is
important for nuclei near the drip-line has been taken into account. The
theoretical as well as the neutron, proton, and matter radii are
presented and compared with the experimental values where they exist. The
change of the potential surface with the neutron number has been investigated.
The diffuseness of the potentials in tin isotopes is analyzed through the
spin-orbital splitting in order to provide new way to understand the halo
phenomena in exotic nuclei. The systematic of the isospin and energy dependence
of these results are extracted and analyzed.Comment: 11 figure
Finite Nuclei in a Relativistic Mean-Field Model with Derivative Couplings
We study finite nuclei, at the mean-field level, using the Zimanyi-Moskowski
model and one of its variations (the ZM3 model). We calculate energy levels and
ground-state properties in nuclei where the mean-field approach is reliable.
The role played by the spin-orbit potential in sorting out mean-field model
descriptions is emphasized.Comment: 17 pages, 9 figures, 30 kbytes. Uses EPSF.TEX. To appear in Zeit. f.
Phys. A (Hadrons and Nuclei
Neutron star properties in a chiral SU(3) model
We investigate various properties of neutron star matter within an effective
chiral model. The predictions of this model are
compared with a Walecka-type model. It is demonstrated that the importance of
hyperon degrees are strongly depending on the interaction used, even if the
equation of state near saturation density is nearly the same in both models.
While the Walecka-type model predicts a strange star core with strangeness
fraction , the chiral model allows only for
and predicts that , and will not exist in star, in
contrast to the Walecka-type model.Comment: 13 pages, Revtex, 5 figs include
Identical Bands in Superdeformed Nuclei: A Relativistic Description
Relativistic Mean Field Theory in the rotating frame is used to describe
superdeformed nuclei. Nuclear currents and the resulting spatial components of
the vector meson fields are fully taken into account. Identical bands in
neighboring Rare Earth nuclei are investigated and excellent agreement with
recent experimental data is observed.Comment: 11 pages (Latex) and 4 figures (available upon request)
TUM-ITP-Ko93/
Liquid-gas phase transition in nuclei in the relativistic Thomas-Fermi theory
The equation of state (EOS) of finite nuclei is constructed in the
relativistic Thomas-Fermi theory using the non-linear
model. The caloric curves are calculated by confining the nuclei in the
freeze-out volume taken to be a sphere of size about 4 to 8 times the normal
nuclear volume. The results obtained from the relativistic theory are not
significantly different from those obtained earlier in a non-relativistic
framework. The nature of the EOS and the peaked structure of the specific heat
obtained from the caloric curves show clear signals of a liquid-gas phase
transition in finite nuclei. The temperature evolution of the Gibbs potential
and the entropy at constant pressure indicate that the characteristics of the
transition are not too different from the first-order one.Comment: RevTex file(19 pages) and 12 psfiles for fugures. Physical Review C
(in Press
In-medium meson effects on the equation of state of hot and dense nuclear matter
The influence of the in-medium mesons on the effective nucleon mass and in
turn on the equation of state of hot/dense nuclear matter is discussed in the
Walecka model. Due to the self-consistent treatment of couplings between
nucleons and and mesons, the temperature and density
dependence of the effective hadron masses approaches more towards the Brown-Rho
scaling law, and the compression modulus is reduced from in mean
field theory to an accepted value .Comment: 5 pages, 6 figures in Revtex. Final version to be publishe
Relativistic Hartree-Bogoliubov Approach for Nuclear Matter with Non-Linear Coupling Terms
We investigate the pairing property of nuclear matter with Relativistic
Hartree-Bogoliubov(RHB) approach. Recently, the RHB approach has been widely
applied to nuclear matter and finite nuclei. We have extended the RHB approach
to be able to include non-linear coupling terms of mesons. In this paper we
apply it to nuclear matter and observe the effect of non-linear terms on
pairing gaps.Comment: 13 pages, 5 figure
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