arXiv subjects

W. F. Chagas-Filho

Publications and source records attributed to W. F. Chagas-Filho.

7 recordsLinked to original sources

arXiv2021

Black Holes, Gravitational Waves and Quantum Gravity

Loop Quantum Gravity is a theory that attempts to describe the quantum mechanics of the gravitational field based on the canonical quantization of General Relativity. According to Loop Quantum Gravity, in a gravitational field, geometric quantities such as area and volume are quantized in terms of the Planck lenth. In this paper we present the basic ideas for a future, mathematically more rigorous, attempt to combine black holes and gravitational waves using the quantization of geometric quantities introduced by Loop Quantum Gravity.

gr-qc↗

arXiv2019

Gravitational Waves and Loop Quantum Gravity

Loop Quantum Gravity is a formalism for describing the quantum mechanics of the gravitational field based on the canonical quantization of General Relativity. The most important result of LQG is that geometric quantities such as area and volume are not arbitrary but are quantized in terms of a minimum length. In this paper we investigate the effect of a minimum length in wave propagation. We find that the minimum length, combined with the constancy of the speed of light, induces a quantization of the energy of a gravitational wave.

gr-qc↗

arXiv2017

Loop Quantum Gravity in the Momentum Representation

We present a generalization of the first-order formalism used to describe the dynamics of a classical system. The generalization is then applied to the first-order action that describes General Relativity. As a result we obtain equations that can be interpreted as describing quantum gravity in the momentum representation.

gr-qc↗

arXiv2004

Relativistic Particles and Commutator Algebras

We construct the vector fields associated to the space-time invariances of relativistic particle theory in flat Euclidean space-time. We show that the vector fields associated to the massive theory give rise to a differential operator realization of the Poincare algebra, while the vector fields associated to the massless theory, including the space-time supersymmetric sector, allow extensions of the conformal algebra in terms of commutators.

hep-th↗

arXiv2004

Free massless particles and extended space-time algebra

We study the space-time invariances of the relativistic particle action for both the massive and massless cases. While the massive action has only the invariances associated to the Poincare algebra, we find that the invariances of the massless action give rise to the conformal algebra in four dimensions. For the free massless particle, a new invariance of the action permits the construction of an extension of the conformal algebra. The conclusion is that two distinct symmetry breaking mechanisms are necessary to arrive at the Poincare algebra.

hep-th↗

arXiv2003

Relativistic Particles And The Cosmological Constant

We study a general relativistic particle action obtained by incorporating the Hamiltonian constraints into the formalism as a toy model for general relativity and string theory. We show how a non-vanishing cosmological constant and a weakening of gravity at short distances may be interpreted as evidences for the existence of gravitational dipoles.

hep-th↗

arXiv2003

Symmetries in particle and string theories

We study the space-time invariances of the bosonic relativistic particle and bosonic relativistic string using general formulations obtained by incorporating the Hamiltonian constraints into the formalism. We point out that massless particles and tensionless strings have a larger set of space-time invariances than their massive and tensionful partners, respectively. We also show that it is possible to use the reparametrization invariance of the string formulation we present to reach the classical conformal equations of motion without the use of two-dimensional Weyl scalings of the string world sheet. Finally, we show that it is possible to fix a gauge with an enlarged number of space-time invariances in which every point of the free tensionless string moves as if it were an almost-free massless particle. The existence of such a string motion agrees with what is expected from gauge theory-string duality.

hep-th↗