1,311 research outputs found
Gauge Field Emergence from Kalb-Ramond Localization
A new mechanism, valid for any smooth version of the Randall-Sundrum model,
of getting localized massless vector field on the brane is described here. This
is obtained by dimensional reduction of a five dimension massive two form, or
Kalb-Ramond field, giving a Kalb-Ramond and an emergent vector field in four
dimensions. A geometrical coupling with the Ricci scalar is proposed and the
coupling constant is fixed such that the components of the fields are
localized. The solution is obtained by decomposing the fields in transversal
and longitudinal parts and showing that this give decoupled equations of motion
for the transverse vector and KR fields in four dimensions. We also prove some
identities satisfied by the transverse components of the fields. With this is
possible to fix the coupling constant in a way that a localized zero mode for
both components on the brane is obtained. Then, all the above results are
generalized to the massive form field. It is also shown that in general an
effective and forms can not be localized on the brane and we have
to sort one of them to localize. Therefore, we can not have a vector and a
scalar field localized by dimensional reduction of the five dimensional vector
field. In fact we find the expression which determines what forms
will give rise to both fields localized. For , as expected, this is valid
only for the KR field.Comment: Improved version. Some factors corrected and definitions added. The
main results continue vali
New Analytical Solutions for Bosonic Field Trapping in Thick Branes
New analytical solutions for gravity, scalar and vector field localization in
Randall-Sundrum(RS) models are found. A smooth version of the warp factor with
an associated function inside the walls () is
defined, leading to an associated equation and physical constraints on the
continuity and smoothness of the background resulting in a new space of
analytical solutions. We solve this associated equation analytically for the
parabolic and P\"oschl-Teller potentials and analyze the spectrum of resonances
for these fields. By using the boundary conditions we are able to show that,
for any of these solutions, the density probability for finding a massive mode
in the membrane has a universal behavior for small values of mass given by
. As a
consequence, the form of the leading order correction, for example, to the
Newton's law is general and does not depend on the potential used. At the end
we also discuss why complications arises when we try to use the method to find
analytical solutions to the fermion case.Comment: 11 pages, 4 figures; v2: extended version; references and section
added; title, conclusions and abstract change
Efeito da suplemantacao alimentar sobre o comportamento reprodutivo de tourinhos Canchim. I. caracteristicas puberais.
Avaliacao do efeito da suplentacao alimentar durante o periodo seco sobre a puberdade de tourinhos Canchim
Dependence of the Black-body Force on Spacetime Geometry and Topology
In this paper we compute the corrections to the black-body force (BBF)
potential due to spacetime geometry and topology. This recently discovered
attractive force on neutral atoms is caused by the thermal radiation emitted
from black bodies and here we investigate it in relativistic gravitational
systems with spherical and cylindrical symmetries. For some astrophysical
objects we find that the corrected black-body potential is greater than the
flat case, showing that this kind of correction can be quite relevant when
curved spaces are considered. Then we consider four cases: The Schwarzschild
spacetime, the global monopole, the non-relativistic infinity cylinder and the
static cosmic string. For the spherically symmetric case of a massive body, we
find that two corrections appear: One due to the gravitational modification of
the temperature and the other due to the modification of the solid angle
subtended by the atom. We apply the found results to a typical neutron star and
to the Sun. For the global monopole, the modification in the black-body
potential is of topological nature and it is due to the central solid angle
deficit that occurs in the spacetime generated by that object. In the
cylindrical case, which is locally flat, no gravitational correction to the
temperature exists, as in the global monopole case. However, we find the
curious fact that the BBF depends on the topology of the spacetime through the
modification of the azimuthal angle and therefore of the solid angle. For the
static cosmic string we find that the force is null for the zero thickness
case.Comment: 8 pages, 5 figures. Revised versio
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