318 research outputs found
Parametric phenomena of the particle dynamics in a periodic gravitational wave field
We establish exactly solvable models for the motion of neutral particles,
electrically charged point and spin particles (U(1) symmetry), isospin
particles (SU(2) symmetry), and particles with color charges (SU(3) symmetry)
in a gravitational wave background. Special attention is devoted to parametric
effects induced by the gravitational field. In particular, we discuss
parametric instabilities of the particle motion and parametric oscillations of
the vectors of spin, isospin, and color charge.Comment: 26 pages, to be published in J. Math. Phy
Axion-induced oscillations of cooperative electric field in a cosmic magneto-active plasma
We consider one cosmological application of an axionic extension of the
Maxwell-Vlasov theory, which describes axionically induced oscillatory regime
in the state of global magnetic field evolving in the anisotropic expanding
(early) universe. We show that the cooperative electric field in the
relativistic plasma, being coupled to the pseudoscalar (axion) and global
magnetic fields, plays the role of a regulator in this three-level system; in
particular, the cooperative (Vlasov) electric field converts the regime of
anomalous growth of the pseudoscalar field, caused by the axion-photon coupling
at the inflationary epoch of the universe expansion, into an oscillatory regime
with finite density of relic axions. We analyze solutions to the dispersion
equations for the axionically induced cooperative oscillations of the electric
field in the relativistic plasma.Comment: 7 pages, misprints correcte
Non-minimal coupling of photons and axions
We establish a new self-consistent system of equations accounting for a
non-minimal interaction of gravitational, electromagnetic and axion fields. The
procedure is based on a non-minimal extension of the standard
Einstein-Maxwell-axion action. The general properties of a ten-parameter family
of non-minimal linear models are discussed. We apply this theory to the models
with pp-wave symmetry and consider propagation of electromagnetic waves
non-minimally coupled to the gravitational and axion fields. We focus on exact
solutions of electrodynamic equations, which describe quasi-minimal and
non-minimal optical activity induced by the axion field. We also discuss
empirical constraints on coupling parameters from astrophysical birefringence
and polarization rotation observations.Comment: 31 pages, 2 Tables; replaced with the final version published in
Classical and Quantum Gravit
Optical activity induced by curvature in a gravitational pp-wave background
We study optical activity induced by curvature. The optical activity model we
present has two phenomenological gyration parameters, within which we analyze
three model cases, namely, an exactly integrable model, the Landau-Lifshitz
model and the Fedorov model, these latter two are solved in the short
wavelength approximation. The model background is a gravitational pp-wave. The
solutions show that the optical activity induced by curvature leads to Faraday
rotation.Comment: 16 pages, late
Non-minimal electrodynamics and resonance interactions in relativistic plasma
A three-parameter toy-model, which describes a non-minimal coupling of
gravity field with electromagnetic field of a relativistic two-component
electrically neutral plasma, is discussed. Resonance interactions between
particles and transversal waves in plasma are shown to take place due to the
curvature coupling effect.Comment: 6 pages, no figures, the short version of the talk at RUSGRAV-13, to
be published in Gravitation and Cosmology, 2009, No.
Geodesic deviation in pp-wave spacetimes of quadratic curvature gravity
We write the equation of geodesic deviations in the spacetime of -waves
in terms of the Newman-Penrose scalars and apply it to study gravitational
waves in quadratic curvature gravity. We show that quadratic curvature gravity
-waves can have a transverse helicity-0 polarization mode and two
transverse helicity-2 general relativity-like wave polarizations. A concrete
example is given in which we analyze the wave polarizations of an exact
impulsive gravitational wave solution to quadratic curvature gravity.Comment: 16 pages, no figures, accepted in Physical Review
Electromagnetic waves in an axion-active relativistic plasma non-minimally coupled to gravity
We consider cosmological applications of a new self-consistent system of
equations, accounting for a nonminimal coupling of the gravitational,
electromagnetic and pseudoscalar (axion) fields in a relativistic plasma. We
focus on dispersion relations for electromagnetic perturbations in an initially
isotropic ultrarelativistic plasma coupled to the gravitational and axion
fields in the framework of isotropic homogeneous cosmological model of the de
Sitter type. We classify the longitudinal and transversal electromagnetic modes
in an axionically active plasma and distinguish between waves (damping,
instable or running), and nonharmonic perturbations (damping or instable). We
show that for the special choice of the guiding model parameters the
transversal electromagnetic waves in the axionically active plasma,
nonminimally coupled to gravity, can propagate with the phase velocity less
than speed of light in vacuum, thus displaying a possibility for a new type of
resonant particle-wave interactions.Comment: 19 pages, 9 figures, published versio
Gravity and Electromagnetism with -type Coupling and Magnetic Monopole Solutions
We investigate -type coupling of electromagnetic fields to
gravity. After we derive field equations by a first order variational principle
from the Lagrangian formulation of the non-minimally coupled theory, we look
for static, spherically symmetric, magnetic monopole solutions. We point out
that the solutions can provide possible geometries which may explain the
flatness of the observed rotation curves of galaxies.Comment: 10 page
Non-minimal Wu-Yang wormhole
We discuss exact solutions of three-parameter non-minimal Einstein-Yang-Mills
model, which describe the wormholes of a new type. These wormholes are
considered to be supported by SU(2)-symmetric Yang-Mills field, non-minimally
coupled to gravity, the Wu-Yang ansatz for the gauge field being used. We
distinguish between regular solutions, describing traversable non-minimal
Wu-Yang wormholes, and black wormholes possessing one or two event horizons.
The relation between the asymptotic mass of the regular traversable Wu-Yang
wormhole and its throat radius is analysed.Comment: 9 pages, 2 figures, typos corrected, 2 references adde
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