arXiv subjects
Publications and source records attributed to L. C. Garcia de Andrade.
Oscillating phases in Bianchi type IX anisotropic universes are obtained as linearized solutions of Einstein-Cartan theory of gravity.Instead of making use of Weyssenhoff spinning fluids we addopt axionic torsion matter where the torsion tensor is totally skew-symmetric as in Kalb-Rammond type theories.Spin-torsion,metric and matter density oscillate at different phases.
Cosmological limits on Lorentz invariance breaking in Chern-Simons $(3+1)-dimensional$ electrodynamics are used to place limits on torsion. Birefrigence phenomena is discussed by using extending the propagation equation to Riemann-Cartan spacetimes instead of treating it in purely Riemannian spaces. The parameter of Lorentz violation is shown to be proportional to the axial torsion vector which allows us to place a limit on cosmological background torsion from the Lorentz violation constraint which is given by $ 10^{-33} eV <|S^μ| < 10^{-32} eV$ where $|S^μ|$ is the axial torsion vector.
Nodland Ralston (PRL,1997) investigated the cosmological anisotropy of electromagnetic fields.In this paper we show that it is possible obtain a torsion correction to Nodland-Ralston action starting from the massive Proca electrodynamics in Riemannian spacetime and performing the minimal coupling with torsion.We end up with an action which contains the Nodland Ralston action without breaking the gauge invariance.This mechanism however gives a photon a mass generated by the nonlinear torsion terms.The torsion vector is along the cosmic rotation axis and interacts with the massive photon.This method which breaks conformal invariance allow us to determine a primordial torsion of the order $10^{-29}eV$ from the well-known photon mass limits.
Torsion gravitational effects in the quantum interference of charged particles are investigated. The influence of axial torsion in the Schiff-Banhill effect (SB) inside a metallic shell is given. The effect of torsion on the surface of the earth on (SB) experiment is estimated. Torsion gravity effects on the Sagnac phase-shift of neutron interferometry are also computed.
Bluhm-Kostelecky (BK) Lagrangian to test Lorentz violation with spin-polarised test bodies is shown to be transformed to a torsion-coupling constant Lagrangian by taking into account the Fock-Ivanenko coefficients in spinor form. In this way one is able to introduce torsion in their Lagrangian and make use of the value of their coupling constant to infer that torsion maybe observed in this type of spin-polarised body experiment.The theory would be a low-energy limit of a quasi-Riemannian gravity in Riemann-Cartan spacetime previously proposed by Gasperini.In this theory of gravity Lorentz local gauge symmetry is violated while global coordinate transformations are preserved.Torsion coupling obtained in this way could be as high as $10^{-29} GeV$.
A new class of spacetime defect solutions of Einstein Field equations of Edelen's direct Poincaré Gauge Field theory without biaxial symmetry is presented. The interior solution describes a core of defects where curvature vanishes and Cartan torsion is nonvanishing. Outside the core (in vacuum) the solution represents a spacetime with vanishing curvature and torsion describing a nontrivial topological defect solution of Einstein equations of gravity. Our solution corresponds to a very weak strenght of Tachyons can be found far away from the core defect.
Spin-polarised cylindrically symmetric solution are shown not to be compatible with teleparallel gravity.This can be done in two distinct manners.The first is to show that not all components of the orthonormal tetrad (OT).It is argue however that this result maybe done by a bad choice of the spin distribution along the cylinder.A cylindrically symmetric Riemannian solution is obtained which represents a conical geometry of defects.
Cosmological inflation is discussed in the realm of Einstein-Cartan-Brans-Dicke (ECBD) gravity by constructing an effective inflaton potential and computing the number of e-folds.It is shown that spin-torsion density contributes to a decrease on the number of e-folds of inflation when the ratio of spin-torsion density to matter density is aprecciable as happens in the Early Universe.Quantum fluctuations of spin and inflatons are also investigated.Our results seems to be in agreement with Palle's proposal that quantum fluctuations of spin may trigger the primordial era of the universe.The main esult of the paper is the appearence of a supersymmetric type inflaton potential from the ECBD gravity where the coefficient of the one-loop type correction is a constant spin-torsion density.
Closed Time-like curves (CTC) in Cosmic strings in teleparallel $T_{4}$ gravity are forbidden.This result shown here in $T_{4}$ was shown by Soleng (Phys.Rev.D49 (1994)1124) also to be valid in Einstein-Cartan (EC) gravity.Here we show that in $T_{4}$ to allow for CTC we are also led to a lower bound on the angular momentum of the cosmic string.This result is obtained by matching the interior $T_{4}$ solution to a General Relativity (GR) vacuum solution.One of the main differences of the present report and the one by Soleng is that here the interior symmetric solution does not have necessary polarized spins but only Cartan torsion in the spirit of teleparallelism.Torsion flux is computed and it is show that the center of cylinder singularity corresponds to a 2+1 spacetime rotating point particle in $T_{4}$.Therefore the possibility of building time machines seems to be strongly constraint than in the case of EC gravity.
Cosmic strings inside Schwarzschild black holes in teleparallel gravity are considered.Torsion flux inside the black hole is compute like a torsion vortex on a superfluid.Since some components of torsion are singular on Schwarzschild horizon and others remain finite we compute a torsion invariant to decide whether the torsion is singular and where torsion singularities located.It is found out that as in the curvature case of Einstein's black hole the event horizon is not a mere coordinate singularity for torsion although a true torsion singularity is found at the center of the teleparallel black hole.Torsion flux vanishes along the cosmic string itself.It is shown from Cartan equation in differential forms that the spins inside the black hole are polarized along the torsion string.Torsion string seems to be confined inside the black hole.
A teleparallel Gödel universe is shown to lead to a simple and natural relation between Cartan torsion and the global rotation of the universe.This is straightforward if one uses the formalism of Cartan's calculus of exterior differential forms.It is possible to place a limit on the global rotation from the knowledge of torsion and the converse is also true.The Obukhov recent limit of $\fracω{H_{0}}=1$ leads to the well know value for cosmological torsion of $10^{-17} cm^{-1}$.COBE constraints on the temperature anisotropy allows us to obtain limits on the torsion fluctuation in Gödel's universe.
Spin-Polarised cylinders with and without axial magnetic fields are obtained as particular families of solutions of Einstein-Cartan gravity (EC).The first solution represents a spin-polarised cylinder in teleparallel gravity.The second solution is a magnetized solution representing a spin-polarised cylinder where the magnetic fields and spins are distributed along the infinite axis of the cylinder.Altough it seems that the first solution is less realist than the second it could be obtained by shielding the magnetic fields with a superconductor.The second solution is computed by taking into account the Ritter et al. experiment with the test spin-polarized mass to test spin dependent forces.Ritter experiment deals with a test mass with $>10^{23}$ spin polarized electrons which leads to a spin density of $10^{-4}gcm^{-1}s^{-1}$.
The spin-torsion fluctuations are shown to act as source of decay of inhomogeneities in the early stages of inflationary de Sitter universe.This seems to be a resul of the repulsive nature of the spin-torsion effects.This result is shown through the investigation of the evolution equation of density perturbations in Einstein-Cartan cosmology.We also show that it is possible to place limits on torsion in the universe from the CMBR temperature anisotropy from the computations we made.The decay of inhomogeneities is not enough however to stop the structure formation as galaxies because the growth of inhomogeneitis dominates the torsion effects and the only effect of torsion seems to decrease very weakly the speed of formation of galaxies.
A rotating universe represented by the Gödel metric in spacetimes with Cartan torsion is investigated where the Cosmic Microwave Background Radiation (CMBR) is computed from the Gödel rotation of the universe and the spin density of the spinning fluid in Einstein-Cartan gravity.The autoparallel equation in Riemann-Cartan spacetime is shown to lead to the evolution equation of the cosmological perturbation where the spin-rotation coupling is the source of the growth of inhomogeneities.It is shown that temperature anisotropy is within the limits of COBE constraint yielding a value of $\frac{δT}{T}=10^{-7}$.This result opens the possibility of testing Einstein-Cartan gravity from a cosmological experiment such as PLANCK or MAP.
Two metric perturbations in Einstein-Cartan cosmology are examined.The first case is the scalar mode perturbation of de Sitter metric in Einstein-Cartan cosmology.In this case small perturbations of de Sitter metric shows that this metric is unstable for a universe with spin-torsion density and dilaton fields.In the second case we show that the Friedmann metric in the same space is also unstable under the small perturbations.
Density linear perturbations in Einstein-Cartan two fluid cosmologies where the outer model is an isotropic Friedmann solution with closed model while the inner model is a flat anisotropic Einstein-Cartan (EC) cosmology with shear are computed by taking into consideration superhorizon situations.This situation is in agreement with the present isotropy of the Cosmic Background Radiation where the anisotropic EC model evolves into an isotropic general relativistic model.Galaxy formation is discussed based on this model.Another type of two fluid is considered where the inner solution is a pressureless Kasner type solution while the outer solution is a de Sitter solution with spin and torsion.
We show that it is possible to construct a consistent model describing a current-carrying cosmic string endowed with torsion. The torsion contribution to the gravitational force and geodesics of a test-particle moving around the SCCS are analyzed. In particular, we point out two interesting astrophysical phenomena in which the higher magnitude force we derived may play a critical role: the dynamics of compact objects orbiting the torsioned SCCS and accretion of matter onto it. The deficit angle associated to the SCCS can be obtained and compared with data from the Cosmic Background Explorer (COBE) satellite. We also derived a value for the torsion contribution to matter density fluctuations in the early Universe.
The evolution equation of cosmic density perturbation of a spin dominated universe in Einstein-Cartan gravity is obtained.Examples of inflationary cosmologies with spin are also given where we compute the density perturbations in terms of redshift and show that spin-torsion effects produce a growth on the inhomogeneity of the universe as the redshift is high.Spin-torsion effects are redshifted out when the Universe expands and would be rarely of importance in present day phase of the universe.Comparison with the primordial density fluctuation of COBE data is also obtained.From our computations a COBE type experiment could be proposed to measure the spin-torsion effects in large scale structure objects such as spiral Galaxies and globular clusters.