174 research outputs found
Black holes and the classical model of a particle in Einstein non-linear electrodynamics theory
Modified by a logarithmic term, the non-linear electrodynamics (NED) model of
the Born-Infeld (BI) action is reconsidered. Unlike the standard BI action,
this choice provides interesting integrals of the Einstein-NED equations. It is
found that the spherical matching process for a regular black hole entails
indispensable surface stresses that vanish only for a specific value of the BI
parameter. This solution represents a classical model of an elementary particle
whose radius coincides with the horizon. In flat space time, a charged particle
becomes a conducting shell with a radius proportional to the BI parameter.Comment: 11 pages, no figure, To appear in Phys. Lett.
A topological metric in 2+1-dimensions
Real-valued triplet of scalar fields as source gives rise to a metric which
tilts the scalar, not the light cone, in 2+1-dimensions. The topological metric
is static, regular and it is characterized by an integer . The problem is formulated as a harmonic map of Riemannian manifolds in
which the integer equals to the degree of the map.Comment: 4 pages no figure, final version accepted for publication in EPJ
Black holes from multiplets of scalar fields in 2+1- and 3+1-dimensions
We obtain classes of black hole solutions constructed from multiplets of
scalar fields in 2+1 / 3+1 dimensions. The multi-component scalars don't
undergo a symmetry breaking so that only the isotropic modulus is effective.
The Lagrangian is supplemented by a self-interacting potential which plays
significant role in obtaining the exact solutions. In 2+1 / 3+1 dimensions
doublet / triplet of scalars is effective which enriches the available black
hole spacetimes and creates useful Liouville weighted field theoretic models.Comment: 10 pages, 10 figures, final version accepted for publication in EPJ
Reflection of electromagnetic waves from mixtures of plane gravitational and scalar waves
We consider colliding wave packets consisting of hybrid mixtures of
electromagnetic, gravitational and scalar waves. Irrespective of the scalar
field, the electromagnetic wave still reflects from the gravitational wave.
Some reflection processes are given for different choice of packets in which
the Coulomb-like component vanishes. Exact solution for multiple
reflection of an electromagnetic wave from successive impulsive gravitational
waves is obtained in a closed form. It is shown that a succesive sign flip in
the Maxwell spinor arises as a result of encountering with an impulsive train
(i.e. the Dirac's comb curvature) of gravitational waves. Such an observable
effect may be helpful in the detection of gravitational wave bursts.Comment: 20 pages, 3 ps figures, small typos corrected, published versio
Colliding Wave Solutions in a Symmetric Non-metric Theory
A method is given to generate the non-linear interaction (collision) of
linearly polarized gravity coupled torsion waves in a non-metric theory.
Explicit examples are given in which strong mutual focussing of gravitational
waves containing impulsive and shock components coupled with torsion waves does
not result in a curvature singularity. However, the collision of purely torsion
waves displays a curvature singularity in the region of interaction.Comment: 16 pages, 1 ps figure, It will appear in Int. Jour. of Theor. Physic
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