6,676 research outputs found
Towards relativistic quantum geometry
We obtain a gauge-invariant relativistic quantum geometry by using a
Weylian-like manifold with a geometric scalar field which provides a
gauge-invariant relativistic quantum theory in which the algebra of the
Weylian-like field depends on observers. An example for a Reissner-Nordstr\"om
black-hole is studied.Comment: 9 pages, no figures, improved versio
Discrete Modes in Gravitational Waves from the Big-Bang
We develop a new approach to gravitational waves in which the Einstein
equations are governed by the cosmological constant which is related to the
existence of a manifold which is closed. We study an example in which the
matter Lagrangian is described by the scalar (inflaton) field. There are only
three dynamical solutions. In one of them the universe is initially static but
begins to increase until an inflationary stage. We calculate the dynamics of GW
in this primordial pre-inflationary stage of the universe. We found that there
should be an infinite number of polarization modes in order to the fields can
be quantized. Finally, we calculate the energy density due to the gravitational
waves.Comment: Version accepted in Astrophysics Space Scienc
Form invariant transformations between n-- and m-- dimensional flat Friedmann--Robertson--Walker cosmologies
We illustrate how the group of symmetry transformations, which preserve the
form of the n--dimensional flat Friedmann--Robertson--Walker cosmologies
satisfying Einstein equations, acts in any dimension. This group relates the
energy density and the isotropic pressure of the cosmic fluid to the expansion
rate. The freedom associated with the dimension of the space time yields
assisted inflation even when the energy density of the fluid is a dimensional
invariant and enriches the set of duality transformations leading to phantom
cosmologies.Comment: Accepted for publication in Iternational Journal of Modern Physics
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