756 research outputs found
Does Geometric Coupling Generates Resonances?
Geometrical coupling in a co-dimensional one Randall-Sundrum scenario (RS) is
used to study resonances of form fields. The resonances are calculated
using the transfer matrix method. The model studied consider the standard RS
with delta-like branes, and branes generated by kinks and domain-wall as well.
The parameters are changed to control the thickness of the smooth brane. With
this a very interesting pattern is found for the resonances. The geometrical
coupling does not generate resonances for the reduced form in all cases
considered.Comment: 10 pages, 10 figure
Photon mass as a probe to extra dimensions
In this manuscript we show that the geometrical localization mechanism
implies a four dimensional mass for the photon. The consistence of the model
provides a mass given exactly by where is the Ricci
scalar. As a consequence, the cosmological photon has a mass related to the
vacuum solution of the Einstein equation. At the present age of the universe we
have a dS vacuum with , where Lambda is a positive cosmological
constant. With this we find that kg, which
is below the present experimental upper bounds, and such correction may be
observed in the next years with more precise measurements. By considering the
value of inside some astrophysical sources and environments we find that
the bound is also satisfied. The experimental verification of this mass, beyond
pointing to the existence of extra dimensions, would imply in a fundamental
change in cosmology, astrophysics and in particle physics since the same
mechanism is valid for non-abelian gauge fields.Comment: 4 page
Measurement of the 0.511 MeV gamma ray line from the Galactic Center
The detection of the 0.511 MeV electron positron annihilation line coming from the Galactic Center to provide the means to estimate the rate of positron production and to test some theoretical sources of positrons is addressed. The results of the measurements of the 0.511 MeV line flux made with a gamma ray experiment on board a stratospheric balloon are presented. The detector field of view looked at the galactic longitude range -31 deg l(II) +41 deg. The observed flux is 0.0067 (+ or - 0.0005) photons 1/cm(2)5 which is in very good agreement with the expected flux when assuming that the Galactic Center is a line source emitting uniformly
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