129,960 research outputs found
Black hole physics, confining solutions of SU(3)-Yang-Mills equations and relativistic models of mesons
The black hole physics techniques and results are applied to find the set of
the exact solutions of the SU(3)-Yang-Mills equations in Minkowski spacetime in
the Lorentz gauge. All the solutions contain only the Coulomb-like or linear in
components of SU(3)-connection. This allows one to obtain some possible
exact and approximate solutions of the corresponding Dirac equation that can
describe the relativistic bound states. Possible application to the
relativistic models of mesons is also outlined.Comment: 13 pages, LaTeX with using the mpla1.sty file from the package of
World Scientific Publishing C
The formation of the Milky Way halo and its dwarf satellites, a NLTE-1D abundance analysis. I. Homogeneous set of atmospheric parameters
We present a homogeneous set of accurate atmospheric parameters for a
complete sample of very and extremely metal-poor stars in the dwarf spheroidal
galaxies (dSphs) Sculptor, Ursa Minor, Sextans, Fornax, Bo\"otes I, Ursa Major
II, and Leo IV. We also deliver a Milky Way (MW) comparison sample of giant
stars covering the -4 < [Fe/H] < -1.7 metallicity range. We show that, in the
[Fe/H] > -3.5 regime, the non-local thermodynamic equilibrium (NLTE)
calculations with non-spectroscopic effective temperature (Teff) and surface
gravity (log~g) based on the photometric methods and known distance provide
consistent abundances of the Fe I and Fe II lines. This justifies the Fe I/Fe
II ionisation equilibrium method to determine log g for the MW halo giants with
unknown distance. The atmospheric parameters of the dSphs and MW stars were
checked with independent methods. In the [Fe/H] > -3.5 regime, the Ti I/Ti II
ionisation equilibrium is fulfilled in the NLTE calculations. In the log~g -
Teff plane, all the stars sit on the giant branch of the evolutionary tracks
corresponding to [Fe/H] = -2 to -4, in line with their metallicities. For some
of the most metal-poor stars of our sample, we hardly achieve consistent NLTE
abundances from the two ionisation stages for both iron and titanium. We
suggest that this is a consequence of the uncertainty in the Teff-colour
relation at those metallicities. The results of these work provide the base for
a detailed abundance analysis presented in a companion paper.Comment: 25 pages, 7 tables, 7 figures, A&A, accepte
Exploration of Resonant Continuum and Giant Resonance in the Relativistic Approach
Single-particle resonant-states in the continuum are determined by solving
scattering states of the Dirac equation with proper asymptotic conditions in
the relativistic mean field theory (RMF). The regular and irregular solutions
of the Dirac equation at a large radius where the nuclear potentials vanish are
relativistic Coulomb wave functions, which are calculated numerically.
Energies, widths and wave functions of single-particle resonance states in the
continuum for ^{120}Sn are studied in the RMF with the parameter set of NL3.
The isoscalar giant octupole resonance of ^{120}Sn is investigated in a fully
consistent relativistic random phase approximation. Comparing the results with
including full continuum states and only those single-particle resonances we
find that the contributions from those resonant-states dominate in the nuclear
giant resonant processes.Comment: 16 pages, 2 figure
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