27 research outputs found
Geometric back-reaction in pre-inflation from relativistic quantum geometry
The pre-inflationary evolution of the universe describes the beginning of the
expansion from a static initial state, such that the Hubble parameter is
initially zero, but increases to an asymptotic constant value, in which it
could achieve a de Sitter (inflationary) expansion. The expansion is driven by
a background phantom field. The back-reaction effects at this moment should
describe vacuum geometrical excitations, which are studied with detail in this
work using Relativistic Quantum Geometry.Comment: improved versio
Charged and electromagnetic fields from relativistic quantum geometry
In the Relativistic Quantum Geometry (RQG) formalism recently introduced, was
explored the possibility that the variation of the tensor metric can be done in
a Weylian integrable manifold using a geometric displacement, from a Riemannian
to a Weylian integrable manifold, described by the dynamics of an auxiliary
geometrical scalar field , in order that the Einstein tensor (and the
Einstein equations) can be represented on a Weyl-like manifold. In this
framework we study jointly the dynamics of electromagnetic fields produced by
quantum complex vector fields, which describes charges without charges. We
demonstrate that complex fields act as a source of tetra-vector fields which
describe an extended Maxwell dynamics.Comment: improved versio
The Sun was not born in M 67
Using the most recent proper-motion determination of the old,
Solar-metallicity, Galactic open cluster M 67, in orbital computations in a
non-axisymmetric model of the Milky Way, including a bar and 3D spiral arms, we
explore the possibility that the Sun once belonged to this cluster. We have
performed Monte Carlo numerical simulations to generate the present-day orbital
conditions of the Sun and M 67, and all the parameters in the Galactic model.
We compute 3.5 \times 10^5 pairs of orbits Sun-M 67 looking for close
encounters in the past with a minimum distance approach within the tidal radius
of M 67. In these encounters we find that the relative velocity between the Sun
and M 67 is larger than 20 km/s. If the Sun had been ejected from M 67 with
this high velocity by means of a three-body encounter, this interaction would
destroy an initial circumstellar disk around the Sun, or disperse its already
formed planets. We also find a very low probability, much less than 10^-7, that
the Sun was ejected from M 67 by an encounter of this cluster with a giant
molecular cloud. This study also excludes the possibility that the Sun and M 67
were born in the same molecular cloud. Our dynamical results convincingly
demonstrate that M67 could not have been the birth cluster of our Solar System.Comment: Astronomical Journal accepted (35 pages, 9 figures
OcorrĂŞncia de diapausa em Tenuipalponychus tabebuiae Aguilar, Flechtmann & Ochoa (Acari, Tetranychidae) no Estado de SĂŁo Paulo, Brasil
This paper reports the occurrence of diapause in Tenuipalponychus tabebuiae Aguilar, Flechtmann & Ochoa, 1991, for the first time in tropical region, and describes the morphological differences between the diapausing and no-diapausing females
The Heisenberg spinor field classification and its interplay with the Lounesto’s classification
Dirac linear spinor fields were obtained from non-linear Heisenberg spinors, in the literature. Here we extend that idea by considering not only Dirac spinor fields but spinor fields in any of the Lounesto’s classes. When one starts considering all these classes of fields, the question of providing a classification for the Heisenberg spinor naturally arises. In this work the classification of Heisenberg spinor fields is derived and scrutinized, in its interplay with the Lounesto’s spinor field classification