105 research outputs found
About the isocurvature tension between axion and high scale inflationary models
The present work suggests that the isocurvature tension between axion and
high energy inflationary scenarios may be avoided by considering a double field
inflationary model involving the hidden Peccei-Quinn Higgs and the Standard
Model one. Some terms in the lagrangian we propose explicitly violate the
Peccei-Quinn symmetry but, at the present era, their effect is completely
negligible. The resulting mechanism allows a large value for the axion
constant, of the order , thus the axion isocurvature fluctuations
are suppressed even when the scale of inflation is very high, of the
order of . This numerical value is typical in Higgs
inflationary models. An analysis about topological defect formation in this
scenario is also performed, and it is suggested that, under certain
assumptions, their effect is not catastrophic from the cosmological point of
view
Probing global aspects of a geometry by the self-force on a charge: Spherical thin-shell wormholes
The self-interaction for a static point charge in the space-time of a
thin-shell wormhole constructed connecting two identical Schwarzschild
geometries is calculated in a series expansion. The electrostatic self-force is
evaluated numerically. It is found to be attractive towards the throat except
for some values of the throat radius proximate to the value of the
Schwarzschild horizon for which the force is repulsive or attractive depending
on the position of the charge. The result differs from the self-force in the
space-time of the Schwarzschild black hole, where it is always repulsive from
the center. Although these wormhole and black hole geometries are locally
indistinguishable, the different topologies of both backgrounds are manifested
in the electrostatic field of a point charge.Comment: 17 pages, 4 figue
About gravitational radiation of semi local strings with non compact internal modes
In a previous work [1], given a putative vortex, it was determined whether it
is non abelian or not by studying its radiation channels. The example
considered there was a gauge model whose internal orientational modes
are described by an sphere . The non abelian effects presented in this
reference were not very pronounced, due to the compactness of this space. In
the present work, this analysis is extended for a vortex whose internal space
is non compact. This situation may be realised by semi-local supersymmetric
vortices [2]-[9]. As the internal space has infinite volume, a largely
energetic perturbation may propagate along the object. A specific configuration
is presented, when the internal space is the resolved conifold with its Ricci
flat metric. The curious feature about it is that it corresponds to a static
vortex, that is, the perturbation is only due to the internal modes. Even being
static, the emission of gravitational radiation is in the present case of
considerable order. This suggest that the presence of slowly moving objects
that can emit a large amount of gravitational radiation is a hint of non
abelianity.Comment: 14 pages, no figures, some irrelevant constants were set to one and
the formulas are less cumbersome. Some additional numerical estimation was
include
Functional vision barriers: a new concept analyzed in terms of human visual performance
In this work we introduce a new category of barriers that we call "functional vision barriers." This expression refers to lighting and visual elements that may complicate or hinder functional vision and may make life even more difficult for people with visual defects. These barriers appear as a consequence of certain negative effects caused by the poor design of the visual stimulus or visual environment that surrounds it in which lighting is one of the main factors. We use the term "functional vision" because this expression refers to the ability of the visual system to perform everyday tasks. We analyzed some of our previous results with regard to situations that can be considered "functional vision barriers": (1) stimuli with low luminance contrast information in which the addition of chromatic contrast improves visual performance and (2) tasks that are performed in the presence of a glare source in the visual field, diminishing visual performance and reducing brightness perception.Fil: Colombo, Elisa Margarita. Universidad Nacional de Tucuman. Facultad de Cs.exactas y Tecnologia. Departamento de Luminotecnia, Luz y Vision; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucuman. Instituto de Investigacion En Luz, Ambiente y Vision; ArgentinaFil: O´Donell, Beatriz M.. Universidad Nacional de Tucuman. Facultad de Cs.exactas y Tecnologia. Departamento de Luminotecnia, Luz y Vision; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucuman. Instituto de Investigacion En Luz, Ambiente y Vision; ArgentinaFil: Santillán, Javier Enrique. Universidad Nacional de Tucuman. Facultad de Cs.exactas y Tecnologia. Departamento de Luminotecnia, Luz y Vision; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucuman. Instituto de Investigacion En Luz, Ambiente y Vision; ArgentinaFil: Issolio, Luis Alberto. Universidad Nacional de Tucuman. Facultad de Cs.exactas y Tecnologia. Departamento de Luminotecnia, Luz y Vision; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucuman. Instituto de Investigacion En Luz, Ambiente y Vision; Argentin
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