1,256 research outputs found
Energy spectrum and phase diagrams of two-sublattice hard-core boson model
The energy spectrum, spectral density and phase diagrams have been obtained
for two-sublattice hard-core boson model in frames of random phase
approximation approach. Reconstruction of boson spectrum at the change of
temperature, chemical potential and energy difference between local positions
in sublattices is studied. The phase diagrams illustrating the regions of
existence of a normal phase which can be close to Mott-insulator (MI) or
charge-density (CDW) phases as well as the phase with the Bose-Einstein
condensate (SF phase) are built.Comment: 9 pages, 4 figure
Optical Color Gradients in Star-Forming Ring Galaxies
We compute radial color gradients produced by an outwardly propagating
circular wave of star formation and compare our results with color gradients
observed in the classical ring galaxy, the ``Cartwheel''. We invoke two
independent models of star formation in the ring galaxies. The first one is the
conventional density wave scenario, in which an intruder galaxy creates a
radially propagating density wave accompanied by an enhanced star formation
following the Schmidt law. The second scenario is a pure self-propagating star
formation model, in which the intruder only sets off the first burst of stars
at the point of impact. Both models give essentially the same results.
Systematic reddening of B-V, V-K colors towards the center, such as that
observed in the Cartwheel, can be obtained only if the abundance of heavy
elements in the star-forming gas is a few times below solar. The B-V and V-K
color gradients observed in the Cartwheel can be explained as a result of
mixing of stellar populations born in a star-forming wave propagating through a
low-metallicity gaseous disk, and a pre-existing stellar disk of the size of
the gaseous disk with color properties typical to those observed in nearby disk
galaxies.Comment: 16 pages, 12 figures; accepted for publication in the Astrophysical
Journa
Ferromagnetic Detectors of Axions in RF (S - X) Band
The (pseudo) Goldstone bosons arise naturally in many modern theories such as
supergravity, superstring theory and variants of general relativity with
torsion. By the other hand, there are well known indications that a large part
of the Universe mass exists in a form of dark matter. The most attractive model
of the dark matter is non-relativistic gas of the light elementary particles
weakly interacting with the "usual" matter \cite{b2} - \cite{b4}. We describe
ferromagnetic detectors, for search of arion(axion), where a high-sensitive
two-channel SHF receiver is used. Its sensitivity reaches to ,
with time of accumulation . Fourier analysis of signal provides a
survey in zone up to with spectral resolution .
There was applied a high sensitive SHF receiver based on a special computer
method of coherent accumulation of signals. It is possible to use the receiver
in other precise experiments: measuring of electron/positron beams polarization
in storage rings, investigation of parity violation, investigation of
atmosphere with radars etc.Comment: 6 pages, LaTeX, no figure
- …