1,410 research outputs found
A model for time-dependent cosmological constant and its consistency with the present Friedmann universe
We use a model where the cosmological term can be related to the chiral gauge
anomaly of a possible quantum scenario of the initial evolution of the
universe. We show that this term is compatible with the Friedmann behavior of
the present universe.Comment: 5 pages, Revtex 4, twocolumn (minor corrections and improved
reference list. To appear in Classical and Quantum Gravity
Constructing Dirac linear fermions in terms of non-linear Heisenberg spinors
We show that the massive (or massless) neutrinos can be described as special
states of Heisenberg nonlinear spinors. As a by-product of this decomposition a
particularly attractive consequence appears: the possibility of relating the
existence of only three species of mass-less neutrinos to such internal
non-linear structure. At the same time it allows the possibility that neutrino
oscillation can occurs even for massless neutrinos
Can Non Gravitational Black Holes Exists?
We claim that the existence of a mechanism such that photons may be trapped
in a compact domain is not an exclusive property of gravitational forces. We
show the case in which a non-linear electrodynamics allows such effect. In this
latter case we should call this region an Electromagnetic Black Hole (EBH).Comment: 11 pages, LaTex, no figures, revised versio
Geometrical aspects of light propagation in nonlinear electrodynamics
We analyze the propagation of light in the context of nonlinear
electrodynamics, as it occurs in modified QED vacua. We show that the
corresponding characteristic equation can be described in terms of a
modification of the effective geometry of the underlying spacetime structure.
We present the general form for this effective geometry and exhibit some new
consequences that result from such approach.Comment: LaTex, 11 pages, accepted for publication in Phys. Rev.
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