17 research outputs found
Second Hopf map and supersymmetric mechanics with Yang monopole
We propose to use the second Hopf map for the reduction (via SU(2) group
action) of the eight-dimensional N=8 supersymmetric mechanics to
five-dimensional supersymmetric systems specified by the presence of an SU(2)
Yang monopole. For our purpose we develop the relevant Lagrangian reduction
procedure. The reduced system is characterized by its invariance under the N=5
or N=4 supersymmetry generators (with or without an additional conserved BRST
charge operator) which commute with the su(2) generators.Comment: Final version. To appear in Phys. Rev.
Anisotropic inharmonic Higgs oscillator and related (MICZ-)Kepler-like systems
We propose the integrable (pseudo)spherical generalization of the
four-dimensional anisotropic oscillator with additional nonlinear potential.
Performing its Kustaanheimo-Stiefel transformation we then obtain the
pseudospherical generalization of the MICZ-Kepler system with linear and
potential terms. We also present the generalization of the
parabolic coordinates, in which this system admits the separation of variables.
Finally, we get the spherical analog of the presented MICZ-Kepler-like system.Comment: 7 page
Second Hopf map and Yang-Coulomb system on 5d (pseudo)sphere
Using the second Hopf map, we perform the reduction of the eight-dimensional
(pseudo)spherical (Higgs)oscillator to a five-dimensional system interacting
with a Yang monopole. Then, using a standard trick, we obtain, from the latter
system, the pseudospherical and spherical generalizations of the Yang-Coulomb
system (the five dimensional analog of MICZ-Kepler system). We present the
whole set of its constants of motions, including the hidden symmetry generators
given by the analog of Runge-Lenz vector. In the same way, starting from the
eight-dimensional anisotropic inharmonic Higgs oscillator, we construct the
integrable (pseudo)spherical generalization of the Yang-Coulomb system with the
Stark term.Comment: 10 pages, PACS: 03.65.-w, 02.30.Ik, 14.80.H
Action-angle variables for the particle near extreme Kerr throat
We construct the action-angle variables for the spherical part of conformal
mechanics describing the motion of a particle near extreme Kerr throat. We
indicate the existence of the critical point (with
being the mass of the particle, denoting the speed of light, being the Schwarzschild radius of a black hole with mass
, and denoting the gravitational constant), where these variables
are expressed in terms of elementary functions. Away from this point the
action-angle variables are defined by elliptic integrals.
The proposed formulation allows one to easily reconstruct the whole dynamics
of the particle both in initial coordinates, as well as in the so-called
conformal basis, where the Hamiltonian takes the form of conventional
non-relativistic conformal mechanics.
The related issues, such as semiclassical quantization and
supersymmetrization are also discussed.Comment: 8 pages, PACS numbers: 04.70.Bw, 45.10.Na; we corrected a mistak
Integrable generalizations of oscillator and Coulomb systems via action-angle variables
Oscillator and Coulomb systems on N-dimensional spaces of constant curvature
can be generalized by replacing their angular degrees of freedom with a compact
integrable (N-1)-dimensional system. We present the action-angle formulation of
such models in terms of theradial degree of freedom and the action-angle
variables of the angular subsystem. As an example, we construct the spherical
and pseudospherical generalization of the two-dimensional superintegrable
models introduced by Tremblay, Turbiner and Winternitz and by Post and
Winternitz. We demonstrate the superintegrability of these systems and give
their hidden constant of motion.Comment: 10 pages; v2: formulae for hidden integrals and two refs. added,
typos fixed, published versio
Time-variability in the Interstellar Boundary Conditions of the Heliosphere: Effect of the Solar Journey on the Galactic Cosmic Ray Flux at Earth
During the solar journey through galactic space, variations in the physical
properties of the surrounding interstellar medium (ISM) modify the heliosphere
and modulate the flux of galactic cosmic rays (GCR) at the surface of the
Earth, with consequences for the terrestrial record of cosmogenic
radionuclides. One phenomenon that needs studying is the effect on cosmogenic
isotope production of changing anomalous cosmic ray fluxes at Earth due to
variable interstellar ionizations. The possible range of interstellar ram
pressures and ionization levels in the low density solar environment generate
dramatically different possible heliosphere configurations, with a wide range
of particle fluxes of interstellar neutrals, their secondary products, and GCRs
arriving at Earth. Simple models of the distribution and densities of ISM in
the downwind direction give cloud transition timescales that can be directly
compared with cosmogenic radionuclide geologic records. Both the interstellar
data and cosmogenic radionuclide data are consistent with cloud transitions
during the Holocene, with large and assumption-dependent uncertainties. The
geomagnetic timeline derived from cosmic ray fluxes at Earth may require
adjustment to account for the disappearance of anomalous cosmic rays when the
Sun is immersed in ionized gas.Comment: Submitted to Space Sciences Review
Heliospheric Response to Different Possible Interstellar Environments
At present, the heliosphere is embedded in a warm, low-density interstellar cloud that belongs to a cloud system flowing through the local standard of rest with a velocity near ~18 km s-1. The velocity structure of the nearest interstellar material (ISM), combined with theoretical models of the local interstellar cloud (LIC), suggest that the Sun passes through cloudlets on timescales of â€103-104 yr, so the heliosphere has been, and will be, exposed to different interstellar environments over time. By means of a multifluid model that treats plasma and neutral hydrogen self-consistently, the interaction of the solar wind with a variety of partially ionized ISM is investigated, with the focus on low-density cloudlets such as are currently near the Sun. Under the assumption that the basic solar wind parameters remain/were as they are today, a range of ISM parameters (from cold neutral to hot ionized, with various densities and velocities) is considered. In response to different interstellar boundary conditions, the heliospheric size and structure change, as does the abundance of interstellar and secondary neutrals in the inner heliosphere, and the cosmic-ray level in the vicinity of Earth. Some empirical relations between interstellar parameters and heliospheric boundary locations, as well as neutral densities, are extracted from the models
Habitable Zones in the Universe
Habitability varies dramatically with location and time in the universe. This
was recognized centuries ago, but it was only in the last few decades that
astronomers began to systematize the study of habitability. The introduction of
the concept of the habitable zone was key to progress in this area. The
habitable zone concept was first applied to the space around a star, now called
the Circumstellar Habitable Zone. Recently, other, vastly broader, habitable
zones have been proposed. We review the historical development of the concept
of habitable zones and the present state of the research. We also suggest ways
to make progress on each of the habitable zones and to unify them into a single
concept encompassing the entire universe.Comment: 71 pages, 3 figures, 1 table; to be published in Origins of Life and
Evolution of Biospheres; table slightly revise