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A. C. V. V. de Siqueira

Publications and source records attributed to A. C. V. V. de Siqueira.

15 recordsLinked to original sources
arXiv2022

Mapping Among Line Elements

In this paper, we revisit our paper "Matrix Riccati Equations, Kaluza-Klein, Finsler Spaces, and Mapping Among Manifolds"[1]. We will build mapping among generalized quadratic Hamiltonians and we construct Calabi's Riemmannian Line Elements for non-quadratic and generalized Hamiltonians. As an application, we use conformally flat forms of two general pseudo-Riemannian line elements embedded in two flat manifolds and obtain an analytical and exact solution of the mapping between these two manifolds as well as an infinite set of exact solutions of the associated matrix Riccati equation.

math.DG↗
arXiv2018

Einstein, Weyl and Asymmetric Geometries

In a previous paper, we presented new results on non-Riemannian geometry. For an asymmetric connection, we showed that a projective change in the symmetric part generates a vector field that is not arbitrary, but is the gradient of a non-arbitrary scalar field. As a consequence, Weyl's geometry is a conformal differential geometry and is associated with asymmetric geometry by this projective change. In the present paper, important differences between light-like and non-light-like intervals are analysed. We show that integrability condition in Weyl's geometry implies microscopic spacetime oscillations of Weyl's and Einstein's geometries. We show that the integrability condition in Weyl's geometry, together with the condition that null and massive particles interact locally in an Einstein spacetime. We construct an equation for linear transverse waves and make a qualitative application in a hydrogen atom, which, from qualitative viewpoint, agrees with Bohr's hydrogen model and Schrodinger's quantum mechanics.

physics.gen-ph↗
arXiv2018

Topics in Non-Riemannian Geometry

In this paper, we present some new results on non-Riemannian geometry, more specifically, asymmetric connections and Weyl's geometry. For asymmetric connections, we show that a projective change in the symmetric part generates a vector field that its not arbitrary, as usually presented, but rather, the gradient of a non-arbitrary scalar function. We use normal coordinates for the symmetric part of asymmetric connections as well as for the Weyl's geometry. This has a direct impact on asymmetric conections, although normal frames are usual in antisymmetic connections, unlike normal coordinates. In this symmetric part of asymmetric connections, the vector fields obeys a well-known partial differential equantion, whereas in Weyl's geometry, gauge vector fields obey an equation that we believe is presented for the first time in this paper. We deduce the exact solution of each of these vector fields as the gradient of a scalar function. For both asymmetric and Weyl's symmetric connections, the respective scalar functions obey respective scalar partial differential equations. As a consequence, Weyl's geometry is a conformal differential geometry and is associated with asymmetric geometry by a projective change. We also show that a metric tensor naturally appears in asymmetric geometry and is not introduced via a postulate, as is usually done. In Weyl's geometry, the eletromagnetic gauge is the gradient of a non-arbitrary scalar function and eletromagnetic fields are null. Despide the origin in Weyl's differential geometry, the use of the eletromagnetic gauge is correct in Lagrangean and Hamiltonian formulations of field theories.

gr-qc↗
arXiv2013

Mapping Among Manifolds III

In two previous papers, we constructed two modified Hamiltonian formalisms to make maps among manifolds explicit. In this paper, the two modified formalisms were adapted to manifolds with local coordinates given by scalar fields, as in a classical nonlinear sigma-model. The scalar field coordinates could be built from vectors, tensors, spinors, Lagrangians, Hamiltonians, group parameters, etc.

math-ph↗
arXiv2012

Conformal Form of Pseudo-Riemannian Metrics by Normal Coordinate Transformations II

In this paper, we have reintroduced a new approach to conformal geometry developed and presented in two previous papers, in which we show that all n-dimensional pseudo-Riemannian metrics are conformal to a flat n-dimensional manifold as well as an n-dimensional manifold of constant curvature when Riemannian normal coordinates are well-behaved in the origin and in their neighborhood. This was based on an approach developed by French mathematician Elie Cartan. As a consequence of geometry, we have reintroduced the classical and quantum angular momenta of a particle and present new interpretations. We also show that all n-dimensional pseudo-Riemannian metrics can be embedded in a hyper-cone of a flat n+2-dimensional manifold.

math-ph↗
arXiv2010

Mapping and Embedding of Two Metrics Associated with Dark Matter, Dark Energy, and Ordinary Matter

In this paper we build a mapping between two different metrics and embed them in a flat manifold. One of the metrics represents the ordinary matter, and the other describes the dark matter, the dark energy, and the particle-antiparticle asymmetry. The latter was obtained in a recent paper. For the mapping and embedding, we use two new formalisms developed and presented in two previous papers, Mapping Among Manifolds and, Conformal Form of Pseudo-Riemannian Metrics by Normal Coordinate Transformations, which was a generalization of the Cartan's approach of Riemannian normal coordinates.

gr-qc↗
arXiv2010

A Possible Origin of Dark Matter, Dark Energy, and Particle-Antiparticle Asymmetry

In this paper we present a possible origin of dark matter and dark energy from a solution of the Einstein's equation to a primordial universe, which was presented in a previous paper. We also analyze the Dirac's equation in this primordial universe and present the possible origin of the particle-antiparticle asymmetry. We also present ghost primordial particles as candidates to some quantum vacuum contituents.

gr-qc↗
arXiv2010

Physical Principles Based on Geometric Properties

In this paper we present some results obtained in a previous paper about the Cartan's approach to Riemannian normal coordinates and our conformal transformations among pseudo-Riemannian manifolds. We also review the classical and the quantum angular momenta of a particle obtained as a consequence of geometry, without postulates. We present four classical principles, identifed as new results obtained from geometry. One of them has properties similar Heisemberg's uncertaintly principle and another has some properties similar to Bohr's principle. Our geometric result can be considered as a possible starting point toward a quantum theory without forces.

math-ph↗
arXiv2010

Conformal Form of Pseudo-Riemannian Metrics by Normal Coordinate Transformations

In this paper we extend the Cartan's approach of Riemannian normal coordinates and show that all n-dimensional pseudo-Riemannian metrics are conformal to a flat manifold, when, in normal coordinates, they are well-behaved in the origin and in its neighborhood. We show that for this condition all n-dimensioanl pseudo-Riemannian metrics can be embedded in a hyper-cone of an n+2-dimensional flat manifold. Based on the above conditions we show that each n-dimensional pseudo-Riemannian manifolds is conformal to an n-dimensional manifold of constant curvature. As a consequence of geometry, without postulates, we obtain the classical and the quantum angular momenta of a particle.

math-ph↗
arXiv2008

Mapping Among Manifolds II

In a previous paper we built a modified Hamiltonian formalism to make possible explicit maps among manifolds. In this paper the modified formalism was generalized. As an application, we have built maps among spaces associated to spinors, as well as maps among Kaehler spaces.

math-ph↗
arXiv2008

Mapping among manifolds 1

In this paper we have build the modified Hamiltonian formalism for geometric objects like the Jacobi fields and metric tensors. In this approach Jacobi fields and metric tensors are mapped among manifold. As an application, we have mapped a general n-dimensional Riemannian manifold to a n-dimensional maximally symmetric spacetime.

math-ph↗
arXiv2001

Exact Solutions of Einstein Equations

We use a metric of the type Friedmann-Robertson-Walker to obtain new exact solutions of Einstein equations for a scalar and massive field. The solutions have a permanent or transitory inflationary behavior.

gr-qc↗
arXiv1993

String inspired effective Lagrangian and Inflationary Universe

We consider a string inspired effective Lagrangian for the graviton and dilaton, containing Einstein gravity at the zero slope limit. The numerical solution of the problem shows asymptotically an inflationary universe. The time is measured by the dilaton, as one expects. The result is independent of the introduction of ad-hoc self interactions for the dilaton field.

hep-th↗