652 research outputs found
Dynamical Fermion Masses Under the Influence of Kaluza-Klein Fermions and a Bulk Abelian Gauge Field
The dynamical fermion mass generation on a 3-brane in the 5D space-time is
discussed in a model with bulk fermions in interaction with fermions on the
brane assuming the presence of a constant abelian gauge field component
in the bulk. We calculate the effective potential as a function of the fermion
masses and the gauge field component . The masses can be found from the
stationarity condition for the effective potential (the gap equation). We
formulate the equation for the mass spectrum of the 4D--fermions. The phases
with finite and vanishing fermion masses are studied and the dependence of the
masses on the radius of the 5th dimension is analyzed. The influence of the
-component of the gauge field on the symmetry breaking is considered both
when this field is a background parameter and a dynamical variable. The
critical values of the field, the coupling constant and the radius are
examined.Comment: 9 pages, 4 figure
Radion stabilization from the vacuum on flat extra dimensions
Volume stabilization in models with flat extra dimension could follow from
vacuum energy residing in the bulk when translational invariance is
spontaneously broken. We study a simple toy model that exemplifies this
mechanism which considers a massive scalar field with non trivial boundary
conditions at the end points of the compact space, and includes contributions
from brane and bulk cosmological constants. We perform our analysis in the
conformal frame where the radion field, associated with volume variations, is
defined, and present a general strategy for building stabilization potentials
out of those ingredients. We also provide working examples for the interval and
the orbifold configuration.Comment: Comments and clarifications added throughout the text. Typos
corrected and references added. Final version, 27 pages, five figures
include
Quantum effects from a purely geometrical relativity theory
A purely geometrical relativity theory results from a construction that
produces from three-dimensional space a happy unification of Kaluza's
five-dimensional theory and Weyl's conformal theory. The theory can provide
geometrical explanations for the following observed phenomena, among others:
(a) lifetimes of elementary particles of lengths inversely proportional to
their rest masses; (b) the equality of charge magnitude among all charged
particles interacting at an event; (c) the propensity of electrons in atoms to
be seen in discretely spaced orbits; and (d) `quantum jumps' between those
orbits. This suggests the possibility that the theory can provide a
deterministic underpinning of quantum mechanics like that provided to
thermodynamics by the molecular theory of gases.Comment: 7 pages, LaTeX jpconf.cls (Institute of Physics Publishing), 6
Encapsulated PostScript figures (Fig. 6 is 1.8M uncompressed); Presented at
VI Mexican School on Gravitation and Mathematical Physics "Approaches to
Quantum Gravity
A Note on Segre Types of Second Order Symmetric Tensors in 5-D Brane-world Cosmology
Recent developments in string theory suggest that there might exist extra
spatial dimensions, which are not small nor compact. The framework of most
brane cosmological models is that in which the matter fields are confined on a
brane-world embedded in five dimensions (the bulk). Motivated by this we
reexamine the classification of the second order symmetric tensors in 5--D, and
prove two theorems which collect together some basic results on the algebraic
structure of these tensors in 5-dimensional space-times. We also briefly
indicate how one can obtain, by induction, the classification of symmetric
two-tensors (and the corresponding canonical forms) on n-dimensional spaces
from the classification on 4-dimensional spaces. This is important in the
context of 11--D supergravity and 10--D superstrings.Comment: 12 pages, to appear in Mod. Phys. Lett. A (2003) in the present for
Limits of space-times in five dimensions and their relation to the Segre Types
A limiting diagram for the Segre classification in 5-dimensional space-times
is obtained, extending a recent work on limits of the energy-momentum tensor in
general relativity. Some of Geroch's results on limits of space-times in
general relativity are also extended to the context of five-dimensional
Kaluza-Klein space-times.Comment: Late
Kaluza-Klein dimensional reduction and Gauss-Codazzi-Ricci equations
In this paper we imitate the traditional method which is used customarily in
the General Relativity and some mathematical literatures to derive the
Gauss-Codazzi-Ricci equations for dimensional reduction. It would be more
distinct concerning geometric meaning than the vielbein method. Especially, if
the lower dimensional metric is independent of reduced dimensions the
counterpart of the symmetric extrinsic curvature is proportional to the
antisymmetric Kaluza-Klein gauge field strength. For isometry group of internal
space, the SO(n) symmetry and SU(n) symmetry are discussed. And the
Kaluza-Klein instanton is also enquired.Comment: 15 page
Multipole moments in Kaluza-Klein theories
This paper contains discussion of the problem of motion of extended i.e. non
point test bodies in multidimensional space. Extended bodies are described in
terms of so called multipole moments. Using approximated form of equations of
motion for extended bodies deviation from geodesic motion is derived. Results
are applied to special form of space-time.Comment: 11 pages, AMS-TeX, few misprints corrected, to appear in Classical
and Quantum Gravit
Anisotropic evolution of 5D Friedmann-Robertson-Walker spacetime
We examine the time evolution of the five-dimensional Einstein field
equations subjected to a flat, anisotropic Robertson-Walker metric, where the
3D and higher-dimensional scale factors are allowed to dynamically evolve at
different rates. By adopting equations of state relating the 3D and
higher-dimensional pressures to the density, we obtain an exact expression
relating the higher-dimensional scale factor to a function of the 3D scale
factor. This relation allows us to write the Friedmann-Robertson-Walker field
equations exclusively in terms of the 3D scale factor, thus yielding a set of
4D effective Friedmann-Robertson-Walker field equations. We examine the
effective field equations in the general case and obtain an exact expression
relating a function of the 3D scale factor to the time. This expression
involves a hypergeometric function and cannot, in general, be inverted to yield
an analytical expression for the 3D scale factor as a function of time. When
the hypergeometric function is expanded for small and large arguments, we
obtain a generalized treatment of the dynamical compactification scenario of
Mohammedi [Phys.Rev.D 65, 104018 (2002)] and the 5D vacuum solution of Chodos
and Detweiler [Phys.Rev.D 21, 2167 (1980)], respectively. By expanding the
hypergeometric function near a branch point, we obtain the perturbative
solution for the 3D scale factor in the small time regime. This solution
exhibits accelerated expansion, which, remarkably, is independent of the value
of the 4D equation of state parameter w. This early-time epoch of accelerated
expansion arises naturally out of the anisotropic evolution of 5D spacetime
when the pressure in the extra dimension is negative and offers a possible
alternative to scalar field inflationary theory.Comment: 20 pages, 4 figures, paper format streamlined with main results
emphasized and details pushed to appendixes, current version matches that of
published versio
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