928 research outputs found
Links between different analytic descriptions of constant mean curvature surfaces
Transformations between different analytic descriptions of constant mean
curvature (CMC) surfaces are established. In particular, it is demonstrated
that the system descriptive of CMC surfaces within the
framework of the generalized Weierstrass representation, decouples into a
direct sum of the elliptic Sh-Gordon and Laplace equations. Connections of this
system with the sigma model equations are established. It is pointed out, that
the instanton solutions correspond to different Weierstrass parametrizations of
the standard sphere
Level velocity statistics of hyperbolic chaos
A generalized version of standard map is quantized as a model of quantum
chaos. It is shown that, in hyperbolic chaotic regime, second moment of quantum
level velocity is as predicted by the random matrix theory.Comment: 11 pages, 4 figure
Spontaneous emission of non-dispersive Rydberg wave packets
Non dispersive electronic Rydberg wave packets may be created in atoms
illuminated by a microwave field of circular polarization. We discuss the
spontaneous emission from such states and show that the elastic incoherent
component (occuring at the frequency of the driving field) dominates the
spectrum in the semiclassical limit, contrary to earlier predictions. We
calculate the frequencies of single photon emissions and the associated rates
in the "harmonic approximation", i.e. when the wave packet has approximately a
Gaussian shape. The results agree well with exact quantum mechanical
calculations, which validates the analytical approach.Comment: 14 pages, 4 figure
Photometric, Spectroscopic and Orbital Period Study of Three Early Type Semi-detached Systems: XZ Aql, UX Her and AT Peg
In this paper we present a combined photometric, spectroscopic and orbital
period study of three early-type eclipsing binary systems: XZ Aql, UX Her, and
AT Peg. As a result, we have derived the absolute parameters of their
components and, on that basis, we discuss their evolutionary states.
Furthermore, we compare their parameters with those of other binary systems and
with the theoretical models. An analysis of all available up-to-date times of
minima indicated that all three systems studied here show cyclic orbital
changes, their origin is discussed in detail. Finally, we performed a frequency
analysis for possible pulsational behavior and as a result we suggest that XZ
Aql hosts a {\delta} Scuti component.Comment: 40 pages, 16 figure
Baby Skyrme models for a class of potentials
We consider a class of (2+1) dimensional baby Skyrme models with potentials
that have more than one vacum. These potentials are generalisation of old and
new baby Skyrme models;they involve more complicated dependence on phi_3.We
find that when the potential is invariant under phi_3 -> -phi_3 the
configuration corresponding to the baby skyrmions lying "on top of each other"
are the minima of the energy. However when the potential breaks this symmetry
the lowest field configurations correspond to separated baby skyrmions. We
compute the energy distributions for skyrmions of degrees between one and eight
and discuss their geometrical shapes and binding energies. We also compare the
2-skyrmion states for these potentials. Most of our work has been performed
numerically with the model being formulated in terms of three real scalar
fields (satisfying one constraint).Comment: LaTeX, 14 pages, 10 figure
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