905 research outputs found
4D gravity localized in non Z_2-symmetric thick branes
We present a comparative analysis of localization of 4D gravity on a non
Z_2-symmetric scalar thick brane in both a 5-dimensional Riemannian space time
and a pure geometric Weyl integrable manifold. This work was mainly motivated
by the hypothesis which claims that Weyl geometries mimic quantum behaviour
classically. We start by obtaining a classical 4-dimensional Poincare invariant
thick brane solution which does not respect Z_2-symmetry along the
(non-)compact extra dimension. The scalar energy density of our field
configuration represents several series of thick branes with positive and
negative energy densities centered at y_0. The only qualitative difference we
have encountered when comparing both frames is that the scalar curvature of the
Riemannian manifold turns out to be singular for the found solution, whereas
its Weylian counterpart presents a regular behaviour. By studying the
transverse traceless modes of the fluctuations of the classical backgrounds, we
recast their equations into a Schroedinger's equation form with a volcano
potential of finite bottom (in both frames). By solving the Schroedinger
equation for the massless zero mode m^2=0 we obtain a single bound state which
represents a stable 4-dimensional graviton in both frames. We also get a
continuum gapless spectrum of KK states with positive m^2>0 that are suppressed
at y_0, turning into continuum plane wave modes as "y" approaches spatial
infinity. We show that for the considered solution to our setup, the potential
is always bounded and cannot adopt the form of a well with infinite walls;
thus, we do not get a discrete spectrum of KK states, and we conclude that the
claim that Weylian structures mimic, classically, quantum behaviour does not
constitute a generic feature of these geometric manifolds.Comment: 13 pages, 4 figures, JHEP forma
Search for dark matter in the Sun with the ANTARES neutrino telescope in the CMSSM and mUED frameworks
ANTARES is the first neutrino telescope in the sea. It consists of a three-dimensional array of 885 photomultipliers to collect the Cherenkov light induced by relativistic muons produced in CC interactions of high energy neutrinos. One of the main scientific goals of the experiment is the search for dark matter. We present here the analysis of data taken during 2007 and 2008 to look for a WIMP signal in the Sun. WIMPs are one of the most popular scenarios to explain the dark matter content of the Universe. They would accumulate in massive objects like the Sun or the Galactic Center and their self-annihilation would produce (directly or indirectly) high energy neutrinos detectable by neutrino telescopes. Contrary to other indirect searches (like with gamma rays or positrons), the search for neutrinos in the Sun is free from other astrophysical contributions, so the interpretation of a potential signal in terms of dark matter is much more robust
Accuracy of the recombination correction factor (ks) in FFF beams for three ion chamber types
Flattening filter free (FFF) beams pose particular
considerations for absolute dosimetry.
• These beams are capable to deliver high doses per pulse
(DPP) which implies special consideration regarding
recombination effects in ionization chambers.
• We wanted to know which type of ionization chamber
(Farmer, Semiflex or Pinpoint) would be more appropriate
for commisioning our new FFF beam
Pinch Technique for Schwinger-Dyson equations
In the context of scalar QED we derive the pinch technique self-energies and
vertices directly from the Schwinger-Dyson equations. After reviewing the
perturbative construction, we discuss in detail the general methodology and the
basic field-theoretic ingredients necessary for the completion of this task.
The construction requires the simultaneous treatment of the equations governing
the scalar self-energy and the fundamental interaction vertices. The resulting
non-trivial rearrangement of terms generates dynamically the Schwinger-Dyson
equations for the corresponding Green's functions of the background field
method. The proof relies on the extensive use of the all-order Ward-identities
satisfied by the full vertices of the theory and by the
one-particle-irreducible kernels appearing in the usual skeleton expansion. The
Ward identities for these latter quantities are derived formally, and several
subtleties related to the structure of the multiparticle kernels are addressed.
The general strategy for the generalization of the method in a non-Abelian
context is briefly outlined, and some of the technical difficulties are
discussed.Comment: 43 pages, 11 figures; title and abstract slightly modified, several
clarifying discussions added; final version to match the one accpted for
publication in JHE
Electrónica de Potencia y Créditos ECTS: Experiencia Piloto y Material Docente Empleado
En esta comunicación se presenta por una parte la adaptación de la asignatura Electrónica de Potencia a créditos ECTS, realizado en la Escuela Politécnica Superior de Jaén dentro de la Experiencia Piloto Andaluza y por otra, un trabajo realizado en el Departamento de Ingeniería Electrónica de la Universidad de Jaén, sobre ésta materia, con el que se pretende potenciar la docencia de la misma; trabajo realizado sobre las diferentes unidades didácticas, en formato electrónico interactivo, incorporando hipertexto, gráficos, enlaces a sitios Web y problemas propuestos con sus correspondientes enlaces a las herramientas de simulación como Mathcad y Pspice
Discovery and Observations of ASASSN-13db, an EX Lupi-Type Accretion Event on a Low-Mass T Tauri Star
We discuss ASASSN-13db, an EX Lupi-type ("EXor") accretion event on the young
stellar object (YSO) SDSS J051011.01032826.2 (hereafter SDSSJ0510)
discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN). Using
archival photometric data of SDSSJ0510 we construct a pre-outburst spectral
energy distribution (SED) and find that it is consistent with a low-mass class
II YSO near the Orion star forming region ( pc). We present
follow-up photometric and spectroscopic observations of the source after the
5.4 magnitude outburst that began in September 2013 and ended
in early 2014. These data indicate an increase in temperature and luminosity
consistent with an accretion rate of yr,
three or more orders of magnitude greater than in quiescence. Spectroscopic
observations show a forest of narrow emission lines dominated by neutral
metallic lines from Fe I and some low-ionization lines. The properties of
ASASSN-13db are similar to those of the EXor prototype EX Lupi during its
strongest observed outburst in late 2008.Comment: 14 pages, 4 figures, 1 table. Updated May 2014 to reflect changes in
the final version published in ApJL. Photometric data presented in this
submission are included as ancillary files. For a brief video explaining this
paper, see http://youtu.be/yRCCrNJnvt
Herramienta de apoyo a la docencia de la energía solar fotovoltaica
Con el siguiente trabajo se pretende colaborar en la formación y difusión de la energía solar fotovoltaica; energía alternativa, para la obtención de electricidad, que ocupa un apartado especial en las acciones clave de la Unión Europea. La Universidad de Jaén cuenta con dos asignaturas optativas, como herramientas para contribuir a estos fines. Estas asignaturas pertenecen al plan de estudios correspondiente a Ingeniero Técnico Industrial. Dichas materias, “Electricidad Fotovoltaica” e “Instalaciones fotovoltaicas” se ofertan a las especialidades de: Mecánica, Electricidad y las Electrónica Industrial. El Curso de Energía SolarFotovoltaica para Internet forma parte de la formación en estas materias contribuyendo a cambiar el método de enseñanza empleado hasta ahora. Permite favorecer el grado de implicación por parte del alumno en el proceso de enseñanza – aprendizaje, además de proporcionar información con la que los alumnos puedan construir su conocimiento
Herramienta software para el cálculo de la radiación solar en superficies con distinta inclinación: ORIENTSOL
Este documento pretende presentar una herramienta software de carácter didáctico que hace más sencillo tanto la enseñanza como el aprendizaje del cálculo de la radiación solar sobre superficies inclinadas. Este concepto forma parte de los contenidos de la asignatura optativa, “Instalaciones fotovoltaicas”. Ésta es ofertada por la Universidad de Jaén en el plan de estudios correspondiente a Ingeniero Técnico Industrial en las especialidades de: Mecánica, Electricidad y Electrónica Industrial
FRW Cosmology From Five Dimensional Vacuum Brans-Dicke Theory
We follow approach of induced matter theory for 5D vacuum BD, introduce
induced matter and potential in 4D hypersurfaces, and employ generalized FRW
type solution. We confine ourselves to scalar field and scale factors be
functions of the time. This makes the induced potential, by its definition,
vanishes. When the scale factor of fifth dimension and scalar field are not
constants, 5D eqs for any geometry admit a power law relation between scalar
field and scale factor of fifth dimension. Hence the procedure exhibits that 5D
vacuum FRW like eqs are equivalent, in general, to corresponding 4D vacuum ones
with the same spatial scale factor but new scalar field and coupling constant.
We show that 5D vacuum FRW like eqs or its equivalent 4D vacuum ones admit
accelerated solutions. For constant scalar field, eqs reduce to usual FRW eqs
with typical radiation dominated universe. For this situation we obtain
dynamics of scale factors for any geometry without any priori assumption. For
nonconstant scalar fields and spatially flat geometries, solutions are found to
be power law and exponential ones. We also employ weak energy condition for
induced matter, that allows negative/positive pressures. All types of solutions
fulfill WEC in different ranges. The power law solutions with negative/positive
pressures admit both decelerating and accelerating ones. Some solutions accept
shrinking extra dimension. By considering nonghost scalar fields and recent
observational measurements, solutions are more restricted. We illustrate that
accelerating power law solutions, which satisfy WEC and have nonghost fields,
are compatible with recent observations in ranges -4/3 < \omega </- -1.3151 and
1.5208 </- n < 1.9583 for dependence of fifth dimension scale factor with usual
scale factor. These ranges also fulfill condition nonghost fields in the
equivalent 4D vacuum BD eqs.Comment: 18 pages, 16 figures, 11 table
Herramienta docente en la asignatura de instalaciones fotovoltaicas (Design SFA v1.0). Adaptación a los créditos ECTS
Este documento pretende presentar una herramienta software de carácter docente orientada al aprendizaje del diseño de Sistemas Fotovoltaicos Autónomos (SFA). Este último forma parte de los contenidos de las asignaturas optativas, “Instalaciones fotovoltaicas” y “Electricidad Fotovoltaica”, ofertadas por la Universidad de Jaén en el plan de estudios correspondiente a Ingeniero Técnico Industrial en las especialidades de: Mecánica, Electricidad y Electrónica Industrial. Así mismo, el diseño de los SFA también conforma un módulo del Máster de Energías Renovables impartido en esta misma Universidad
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