arXiv subjects

L. C. Garcia de Andrade

Publications and source records attributed to L. C. Garcia de Andrade.

108 records · Page 6Linked to original sources

arXiv1999

Global monopoles and massless dilatons in Einstein-Cartan gravity

A global monopole in dilatonic Einstein-Cartan gravity is presented. A linearized solution representing a global monopole interacting with a massless dilaton is found where Cartan torsion does not interact with the monopole Higgs field.Computation of the geodesic equation shows that the monopole-dilaton system generates a repulsive gravitational field.The solution is shown to break the linear approximation for certain values of torsion.

gr-qc↗

arXiv1999

Vacuumless torsion defects

Vacuumless defects in space-times with torsion may be obtained from vacuum defects in spacetimes without torsion.This idea is applied to planar domain walls and global monopoles.In the case of domain walls exponentially decaying Higgs type potentials are obtained.In the case of global monopoles torsion string type singularities are obtained like the string singularities in Dirac monopoles.

gr-qc↗

arXiv1999

Gravitational field of global monopoles in Einstein-Cartan gravity

The gravitational weak field of a global monopole in the Einstein-Cartan theory of gravity is investigated.To obtain this solution we assume that Cartan torsion takes the form of the Newtonian gravitational potential.From the geodesics it is possible to show that the torsionic monopole produces a repulsive gravitational force.

gr-qc↗

arXiv1999

On non-Riemannian Superconductors and torsion loops

The geometrization of electrodynamics is obtained by performing the complex extension of the covariant derivative operator to include the Cartan torsion vector and applying this derivative to the Ginzburg-Landau equation of superfluids and Superconductors.It is shown that the introduction of torsion makes a shift in the symmetry breaking vacuum.Torsion loops are computed from geometrical phases outside the superconductor.Inside the superconductor the torsion vanishes which represents the Meissner effect for torsion geometry. Torsion in general equals the London supercurrent.It is possible to place a limit on the size of superconductor needed to give an estimate to torsion.

gr-qc↗

arXiv1998

On Superconductors,Superfluids and Torsion Vortices

The Meissner effect for superconductors in spacetimes with torsion is revisited. Two new physical interpretations are presented. The first considers the Landau-Ginzburg theory yields a new symmetry-breaking vacuum depending on torsion. In the second interpretation a gravitational Meissner torsional effect where when the Higgs field vanishes, torsion and electromagnetic fields need not vanish and outside the Abrikosov tubes a torsion vector analogous to the Maxwell potential is obtained. The analogy is even stronger if we think that in this case the torsion vector has to be derivable from a torsion potential. Another solution of Landau-Ginzburg equation is shown to lead naturally to the geometrization of the electromagnetism in terms of the torsion field. As an application we show that Landau-Ginzburg equations extended to Cartan spaces allow us to determine torsion in the case when the order parameter is frozen to a minimum. It is shown that the presence of torsion in solid state physics changes the ground state of the superfluid phases.

cond-mat↗

arXiv1998

Chern-Simons electrodynamics in (2+1)-spacetime with torsion

Chern-Simons electrodynamics in 2+1-spacetimes with torsion is investigated. We start from the usual Chern-Simons (CS) electrodynamics Lagrangian and Cartan torsion is introduced in the covariant derivative and by a direct coupling of torsion vector to the CS field. Variation of the Lagrangian with respect to torsion shows that Chern-Simons field is proportional to the product of the square of the scalar field and torsion. The electric field is proportional to torsion vector and the magnetic flux is computed in terms of the time-component of the two dimensional torsion. Contrary to early massive electrodynamics in the present model the photon mass does not depend on torsion.

gr-qc↗

arXiv1998

On Superconductors and Torsion Vortices

The Meissner effect for superconductors in spacetimes with torsion is revisited.Two new physical interpretaions are presented.The first considers the Landau-Ginzburg theory yields a new symmetry-breaking vacuum depending on torsion.In the second interpretation a gravitational Meissner torsional effect where when the Higgs field vanishes, torsion and electromagnetic fields need not vanish and outside the Abrikosov tubes a torsion vector analogous to the Maxwell potential is obtained.The analogy is even stronger if we think that in this case the torsion vector has to be derivable from a torsion potential.Another solution of Landau-Ginzburg equation is shown to lead naturally to the geometrization of the electromagnetism in terms of the torsion field.

cond-mat↗

arXiv1998

Domain walls and torsion potentials

A Lagrangian for flat domain walls in spaces with Cartan torsion and electromagnetic fields is proposed.The Lagrangian is very similar to a recently proposed Lagrangian for domain walls in a Chern-Simons electrodynamics in 2+1 dimensions.We show that in the first approximation of the torsion scalar potential the field equations are reduced to a Klein-Gordon type field equation for the torsion potential and the electromagnetic wave equation.A planar symmetric solution representing a parallel plates electric capacitor interacting with the electric field is given.The photon mass is proportional to the torsion potential and in the time dependent case the angular momentum is computed and is shown to be connected with torsion in analogy with the spin-torsion relation which appears in Einstein-Cartan gravity.When the curvature Ricci scalar is introduced we are able to show that the torsion potential can be associated with Higgs massive vectorial bosons.

gr-qc↗

arXiv1998

Gravitational torsion kinks and thick domain walls

The dynamics of a gravitational torsion kink as a plane symmetric thick domain wall solution of Einstein-Cartan (EC) field equation is given. The spin-torsion energy has to be as high as the gravitational kink potential otherwise torsion will not contribute as an appreciable effect to domain wall.Cartan torsion also contributes to the orthonal pressure of the domain wall.

gr-qc↗

arXiv1998

Torsion modified Plasma Screening in Astrophysics

The torsion modified Maxwell-Proca equations when applied to describe a plasma is shown to lead to a correction to the Debye screening length.For hot new born neutron stars the torsion correction is shown to be significant.This effect may provide an indirect evidence for Torsion.

astro-ph↗

arXiv1998

Torsion and Quantized Vortices

A propagation torsion model for quantized vortices is proposed.The model is applied to superfluids and liquid Helium II.

hep-th↗

arXiv1998

Non-Riemannian Cosmic Walls as Boundaries of Spinning Matter

An example is given of a plane topological defect solution of linearized Einstein-Cartan (EC) field equation representing a cosmic wall boundary of spinning matter. The source of Cartan torsion is composed of two orthogonal lines of static polarized spins bounded by the cosmic plane wall. The Kopczyński- Obukhov - Tresguerres (KOT) spin fluid stress-energy current coincides with thin planar matter current in the static case. Our solution is similar to Letelier solution of Einstein equation for multiple cosmic strings. Due to this fact we suggest that the lines of spinning matter could be analogous to multiple cosmic spinning string solution in EC theory of gravity. When torsion is turned off a pure Riemannian cosmic wall is obtained.

hep-th↗

arXiv1998

Distributional Torsion of Cosmic Walls crossed by Cosmic Strings

Distributional sources of cosmic walls crossed by cosmic strings from Riemann-Cartan (RC) Geometry. The matter density of the planar wall is maximum at the point where the cosmic string crosses the cosmic wall. Cartan torsion is has a support on the cosmic string given by the Dirac $ δ$-function. Off the sources are left with a torsionless vacuum.

gr-qc↗

arXiv1998

Space-time defects :Domain walls and torsion

The theory of distributions in non-Riemannian spaces is used to obtain exact static thin domain wall solutions of Einstein-Cartan equations of gravity. Curvature $ δ$-singularities are found while Cartan torsion is given by Heaviside functions. Weitzenböck planar walls are caracterized by torsion $δ$-singularities and zero curvature. It is shown that Weitzenböck static thin domain walls do not exist exactly as in general relativity. The global structure of Weitzenböck nonstatic torsion walls is investigated.

gr-qc↗

arXiv1998

Distributional torsion of charged domain walls with spin

An exact solution of Einstein-Cartan-Maxwell (ECM) field equations representing a charged domain wall given by the jump on the electric charge and spin density across the wall is obtained from the Riemannian theory of distributions. The Gauss-Coddazzi equations are used to show that spin, charge and Cartan torsion increases the repulsive character of the domain wall. Taub and Vilenkin walls are discussed as well as their relations to wormhole geometry. The electric and torsion fields are constants at the wall.

gr-qc↗

arXiv1998

Geodesics around gravitational dislocations

A technique for generating spherically symmetric dislocation solutions of a direct Poincaré gauge theory of gravity based on homogeneous functions which makes Cartan torsion to vanish is presented.Static space supported dislocation and time dependent solutions are supplied.Photons move along geodesics in analogy to geodesics described by electrons around dislocations in solid state physics.Tachyonic sectors are also found.

gr-qc↗

arXiv1998

On the non-minimal coupling of Riemann-flat Klein-Gordon

On the non-minimal coupling of Riemann-flat Klein-Gordon Fields to Space-time torsion} The energy spectrum of Klein-Gordon particles is obtained via the non-minimal coupling of Klein-Gordon fields to Cartan torsion in the approximation of Riemann-flatness and constant torsion.When the mass squared is proportional to torsion coupling constant it is shown that the splitting of energy does not occur.I consider that only the vector part of torsion does not vanish and that it is constant.A torsion Hamiltonian operator is constructed.The spectrum of Klein-Gordon fields is continuos.

gr-qc↗

arXiv1998

Geodesics on non-Riemannian Geometric theory of Planar Defects

The method of Hamilton-Jacobi is used to obtain geodesics around non- Riemannian planar torsional defects.It is shown that by perturbation expansion in the Cartan torsion the geodesics obtained are parabolic curves along the plane x-z when the wall is located at the plane x-y.In the absence of defects the geodesics reduce to straight lines.The family of parabolas depend on the torsion parameter and describe a gravitationally repulsive domain wall.Torsion here plays the role of the Burgers vector in solid state physics.

gr-qc↗