748 research outputs found
Versal deformations of a Dirac type differential operator
If we are given a smooth differential operator in the variable its normal form, as is well known, is the simplest form
obtainable by means of the \mbox{Diff}(S^1)-group action on the space of all
such operators. A versal deformation of this operator is a normal form for some
parametric infinitesimal family including the operator. Our study is devoted to
analysis of versal deformations of a Dirac type differential operator using the
theory of induced \mbox{Diff}(S^1)-actions endowed with centrally extended
Lie-Poisson brackets. After constructing a general expression for tranversal
deformations of a Dirac type differential operator, we interpret it via the
Lie-algebraic theory of induced \mbox{Diff}(S^1)-actions on a special Poisson
manifold and determine its generic moment mapping. Using a Marsden-Weinstein
reduction with respect to certain Casimir generated distributions, we describe
a wide class of versally deformed Dirac type differential operators depending
on complex parameters
The restricted two-body problem in constant curvature spaces
We perform the bifurcation analysis of the Kepler problem on and .
An analogue of the Delaunay variables is introduced. We investigate the motion
of a point mass in the field of the Newtonian center moving along a geodesic on
and (the restricted two-body problem). When the curvature is small,
the pericenter shift is computed using the perturbation theory. We also present
the results of the numerical analysis based on the analogy with the motion of
rigid body.Comment: 29 pages, 7 figure
Duality properties of indicatrices of knots
The bridge index and superbridge index of a knot are important invariants in
knot theory. We define the bridge map of a knot conformation, which is closely
related to these two invariants, and interpret it in terms of the tangent
indicatrix of the knot conformation. Using the concepts of dual and derivative
curves of spherical curves as introduced by Arnold, we show that the graph of
the bridge map is the union of the binormal indicatrix, its antipodal curve,
and some number of great circles. Similarly, we define the inflection map of a
knot conformation, interpret it in terms of the binormal indicatrix, and
express its graph in terms of the tangent indicatrix. This duality relationship
is also studied for another dual pair of curves, the normal and Darboux
indicatrices of a knot conformation. The analogous concepts are defined and
results are derived for stick knots.Comment: 22 pages, 9 figure
Analytical solutions for two heteronuclear atoms in a ring trap
We consider two heteronuclear atoms interacting with a short-range
potential and confined in a ring trap. By taking the Bethe-ansatz-type
wavefunction and considering the periodic boundary condition properly, we
derive analytical solutions for the heteronuclear system. The eigen-energies
represented in terms of quasi-momentums can then be determined by solving a set
of coupled equations. We present a number of results, which display different
features from the case of identical atoms. Our result can be reduced to the
well-known Lieb-Liniger solution when two interacting atoms have the same
masses.Comment: 6 pages, 6 figure
Semirigid Geometry
We provide an intrinsic description of -super \RS s and -\SR\
surfaces. Semirigid surfaces occur naturally in the description of topological
gravity as well as topological supergravity. We show that such surfaces are
obtained by an integrable reduction of the structure group of a complex
supermanifold. We also discuss the \s moduli spaces of -\SR\ surfaces and
their relation to the moduli spaces of -\s\ \RS s.Comment: 29p
Limits on different Majoron decay modes of Mo and Se for neutrinoless double beta decays in the NEMO-3 experiment
The NEMO-3 tracking detector is located in the Fr\'ejus Underground
Laboratory. It was designed to study double beta decay in a number of different
isotopes. Presented here are the experimental half-life limits on the double
beta decay process for the isotopes Mo and Se for different
Majoron emission modes and limits on the effective neutrino-Majoron coupling
constants. In particular, new limits on "ordinary" Majoron (spectral index 1)
decay of Mo ( y) and Se ( y) have been obtained. Corresponding bounds on the
Majoron-neutrino coupling constant are
and .Comment: 23 pages includind 4 figures, to be published in Nuclear Physics
Recent advances in neutrinoless double beta decay search
Even after the discovery of neutrino flavour oscillations, based on data from
atmospheric, solar, reactor, and accelerator experiments, many characteristics
of the neutrino remain unknown. Only the neutrino square-mass differences and
the mixing angle values have been estimated, while the value of each mass
eigenstate still hasn't. Its nature (massive Majorana or Dirac particle) is
still escaping. Neutrinoless double beta decay (-DBD) experimental
discovery could be the ultimate answer to some delicate questions of elementary
particle and nuclear physics. The Majorana description of neutrinos allows the
-DBD process, and consequently either a mass value could be measured or
the existence of physics beyond the standard should be confirmed without any
doubt. As expected, the -DBD measurement is a very difficult field of
application for experimentalists. In this paper, after a short summary of the
latest results in neutrino physics, the experimental status, the R&D projects,
and perspectives in -DBD sector are reviewed.Comment: 36 pages, 7 figures, To be publish in Czech Journal of Physic
Superfluid toroidal currents in atomic condensates
The dynamics of toroidal condensates in the presence of condensate flow and
dipole perturbation have been investigated. The Bogoliubov spectrum of
condensate is calculated for an oblate torus using a discrete-variable
representation and a spectral method to high accuracy. The transition from
spheroidal to toroidal geometry of the trap displaces the energy levels into
narrow bands. The lowest-order acoustic modes are quantized with the dispersion
relation with . A condensate
with toroidal current splits the co-rotating and
counter-rotating pair by the amount: . Radial dipole excitations are the lowest energy dissipation modes.
For highly occupied condensates the nonlinearity creates an asymmetric mix of
dipole circulation and nonlinear shifts in the spectrum of excitations so that
the center of mass circulates around the axis of symmetry of the trap. We
outline an experimental method to study these excitations.Comment: 8 pages, 8 figure
Non-abelian plane waves and stochastic regimes for (2+1)-dimensional gauge field models with Chern-Simons term
An exact time-dependent solution of field equations for the 3-d gauge field
model with a Chern-Simons (CS) topological mass is found. Limiting cases of
constant solution and solution with vanishing topological mass are considered.
After Lorentz boost, the found solution describes a massive nonlinear
non-abelian plane wave. For the more complicate case of gauge fields with CS
mass interacting with a Higgs field, the stochastic character of motion is
demonstrated.Comment: LaTeX 2.09, 13 pages, 11 eps figure
Search for EC and ECEC processes in Sn and decay of Sn to the excited states of Te
Limits on EC and ECEC processes in Sn and on
decay of Sn to the excited states of Te have
been obtained using a 380 cm HPGe detector and an external source
consisting of natural tin. A limit with 90% C.L. on the Sn half-life of
y for the ECEC(0) transition to the excited
state in Cd (1871.0 keV) has been established. This transition is
discussed in the context of a possible enhancement of the decay rate by several
orders of magnitude given that the ECEC process is nearly degenerate
with an excited state in the daughter nuclide. Prospects for investigating such
a process in future experiments are discussed. The decay
limits for Sn to the excited states of Te were obtained on the
level of y at the 90% C.L.Comment: 17 pages, 5 figure
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