171 research outputs found
Example of a self-consistent solution for a fermion on domain wall
We discuss a self-consistent solution for a fermion coupled to static scalar
field in the form of a kink (domain wall). In particular, we study the case
when the fermion occupies an excited non-zero frequency level in the presence
of the domain wall field. The effect of the domain wall profile distortion is
calculated analytically.Comment: 9 pages, no figures; minor corrections, one reference added, results
unchange
The Zel'dovich effect and evolution of atomic Rydberg spectra along the Periodic Table
In 1959 Ya. B. Zel'dovich predicted that the bound-state spectrum of the
non-relativistic Coulomb problem distorted at small distances by a short-range
potential undergoes a peculiar reconstruction whenever this potential alone
supports a low-energy scattering resonance. However documented experimental
evidence of this effect has been lacking. Previous theoretical studies of this
phenomenon were confined to the regime where the range of the short-ranged
potential is much smaller than Bohr's radius of the Coulomb field. We go beyond
this limitation by restricting ourselves to highly-excited s states. This
allows us to demonstrate that along the Periodic Table of elements the
Zel'dovich effect manifests itself as systematic periodic variation of the
Rydberg spectra with a period proportional to the cubic root of the atomic
number. This dependence, which is supported by analysis of experimental and
numerical data, has its origin in the binding properties of the ionic core of
the atom.Comment: 17 pages, 12 figure
Stable branches of a solution for a fermion on domain wall
We discuss the case when a fermion occupies an excited non-zero frequency
level in the field of domain wall. We demonstrate that a solution exists for
the coupling constant in the limited interval . We
show that indeed there are different branches of stable solution for in
this interval. The first one corresponds to a fermion located on the domain
wall (). The second branch, which belongs to the interval
, describes a polarized fermion off the domain
wall. The third branch with describes an excited antifermion in
the field of the domain wall.Comment: 15 pages, 7 figures, references adde
On decay of large amplitude bubble of disoriented chiral condensate
The time evolution of initially formed large amplitude bubble of disoriented
chiral condensate (DCC) is studied. It is found that the evolution of this
object may have a relatively long pre-decay stage. Simple explanation of such
delay of the DCC bubble decay is given. This delay is related to the existence
of the approximate solutions of multi-soliton type of the corresponding radial
sine-Gordon equation in (3+1) dimensions at large bubble radius.Comment: 6 pages, LaTeX, 5 PostScript figure
Electronic structure, optical and magnetic properties of CoFeGe Heusler alloy films
Optical properties of ferromagnetic half-metallic full-Heusler CoFeGe
alloy are investigated experimentally and theoretically. CoFeGe thin
films were obtained by DC magnetron sputtering and show the saturation
magnetization at =10 K of 5.6 /f.u., close to the value
predicted by the Slater-Pauling rule. First-principles calculations of the
electronic structure and the dielectric tensor are performed using the
full-potential linearized-augmented-plane-wave method in the generalized
gradient (GGA) and GGA+U approximations. The measured interband optical
conductivity spectrum for the alloy exhibits a strong absorption band in the 1
- 4 eV energy range with pronounced fine structure, which agrees well with the
calculated half-metallic spectrum of the system, suggesting a near perfect
spin-polarization in the material.Comment: 6 pages, 9 figure
On U(1)-charged domain walls
A classical field system of two interacting fields -- a real Higgs field and
a complex scalar field -- is considered. It is shown that in such field system
a non-trivial solution exists, which is U(1) charged topological kink. Some
questions of stability of the obtained solution are discussed. An improved
variational procedure for searching of topological U(1) charged solutions is
given.Comment: 16 pages, LaTeX, 4 PostScript figure
Frequency Dispersion of Sound Propagation in Rouse Polymer Melts via Generalized Dynamic Random Phase Approximation
An extended generalization of the dynamic random phase approximation (DRPA)
for L-component polymer systems is presented. Unlike the original version of
the DRPA, which relates the (LxL) matrices of the collective density-density
time correlation fumctions and the corresponding susceptibilities of polymer
concentrated systems to those of the tracer macromolecules and so-called broken
links system (BLS), our generalized DRPA solves this problem for (5xL)x(5xL)
matrices of the coupled susceptibilities and time correlation functions of the
component number, kinetic energy and flux densities. The presented technique is
used to study propagation of sound and dynamic form-factor in disentangled
(Rouse) monodisperse homopolymer melt. The calculated sound velocity and
absorption coefficient reveal substantial frequency dispersion. The relaxation
time is found to be N times less than the Rouse time (N is the degree of
polymerization), which evidences strong dynamic screening because of interchain
interaction. We discuss also some peculiarities of the Brillouin scattering in
polymer melts. Besides, a new convenient expression for the dynamic structural
function of the Rouse chain in (q,p)-representation is found.Comment: 37 pages, 2 appendices, 48 references, 1 figur
Lithium and its isotopic ratio ⁶Li/⁷Li in the atmospheres of sharp-lined roAp stars γ Equulei and HD 166473
The lithium lines at 6708 Å for two sharp-lined roAp stars γ Equ and HD 166473 and at 6103 Å for γ Equ were analyzed in high resolution spectra. Three spectral synthesis codes – STARSP, ZEEMAN2, and SYNTHM – were used. New lines of the rare-earth elements from the DREAM database and lines calculated on the basis of the NIST energy levels were included. Magnetic splitting and other line broadening processes were taken into account. Enhanced abundances of lithium in the atmospheres of the stars and high estimates of ⁶Li/⁷Li ratio (0.2 ÷ 0.5) can be explained by the Galactic Cosmic Ray (GCR) production due to spallation reactions and the preservation of original ⁶Li and ⁷Li by strong magnetic fields
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