4,572 research outputs found
Effect of angular momentum distribution on gravitational loss-cone instability in stellar clusters around massive BH
Small perturbations in spherical and thin disk stellar clusters surrounding
massive a black hole are studied. Due to the black hole, stars with
sufficiently low angular momentum escape from the system through the loss cone.
We show that stability properties of spherical clusters crucially depend on
whether the distribution of stars is monotonic or non-monotonic in angular
momentum. It turns out that only non-monotonic distributions can be unstable.
At the same time the instability in disk clusters is possible for both types of
distributions.Comment: 14 pages, 7 figures, submitted to MNRA
Geometrical Description of the Local Integrals of Motion of Maxwell-Bloch Equation
We represent a classical Maxwell-Bloch equation and related to it positive
part of the AKNS hierarchy in geometrical terms. The Maxwell-Bloch evolution is
given by an infinitesimal action of a nilpotent subalgebra of affine Lie
algebra on a Maxwell-Bloch phase space treated as a homogeneous
space of . A space of local integrals of motion is described using
cohomology methods. We show that hamiltonian flows associated to the
Maxwell-Bloch local integrals of motion (i.e. positive AKNS flows) are
identified with an infinitesimal action of an abelian subalgebra of the
nilpotent subalgebra on a Maxwell- Bloch phase space. Possibilities of
quantization and latticization of Maxwell-Bloch equation are discussed.Comment: 16 pages, no figures, plain TeX, no macro
Electronic structure, magnetic ordering and X-ray magnetic circular dichroism in LaPrCoP phosphides
The electronic structure and magnetic ordering in LaPrCoP
(0, 0.25, and 1) phosphides have been studied theoretically using the fully
relativistic spin-polarized Dirac linear muffin-tin orbital (LMTO)
band-structure method. The X-ray absorption and X-ray magnetic circular
dichroism spectra at the Co and Pr edges have been
investigated theoretically within the framework of the LSDA+ method. The
core-hole effect in the final state as well as the effects of the electric
quadrupole and magnetic dipole transitions have been investigated.
Good agreement with experimental measurements has been found.Comment: 11 pages, 8 figure
Pressure and intermittency in passive vector turbulence
We investigate the scaling properties a model of passive vector turbulence
with pressure and in the presence of a large-scale anisotropy. The leading
scaling exponents of the structure functions are proven to be anomalous. The
anisotropic exponents are organized in hierarchical families growing without
bound with the degree of anisotropy. Nonlocality produces poles in the
inertial-range dynamics corresponding to the dimensional scaling solution. The
increase with the P\'{e}clet number of hyperskewness and higher odd-dimensional
ratios signals the persistence of anisotropy effects also in the inertial
range.Comment: 4 pages, 1 figur
Higgs-inspired corrections to the RG flow in the finite-temperature 3D Georgi-Glashow model and its SU(N)-generalization
The Berezinsky-Kosterlitz-Thouless (BKT) RG flow in the ensemble of monopoles
existing in the finite-temperature (2+1)D Georgi-Glashow model is explored in
the regime when the Higgs field is not infinitely heavy, but its mass is rather
of the same order of magnitude as the mass of the W-boson. The corrections to
the standard RG flow are derived to the leading order in the inverse mass of
the Higgs boson. According to the obtained RG equations, the scaling of the
free-energy density in the critical region and the value of the critical
temperature of the phase transition are found to be unaffected by the
finiteness of the Higgs-boson mass. The evolution of the Higgs mass itself is
also investigated and shown to be rather weak, that enables one to treat this
parameter as a constant. The same analysis is further performed in the
SU(N)-case at N>2, where the RG invariance is demonstrated to hold only
approximately, in a certain sense. Modulo this approximation, the critical
behaviour of the SU(N)-model turns out to be identical to that of the
SU(2)-one.Comment: 12 pages, LaTeX2e, no figure
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