56 research outputs found
Localization of gravity in brane world with arbitrary extra dimensions
We study the induced 4-dimensional linearized Einstein field equations in an
m-dimensional bulk space by means of a confining potential. It is shown that in
this approach the mass of graviton is quantized. The cosmological constant
problem is also addressed within the context of this approach. We show that the
difference between the values of the cosmological constant in particle physics
and cosmology stems from our measurements in two different scales, small and
large.Comment: 8 pages. arXiv admin note: substantial text overlap with
arXiv:gr-qc/0408004, arXiv:gr-qc/0607067, arXiv:0704.1035, arXiv:0707.3558,
arXiv:0710.266
Brane worlds and dark matter
Two problems related to dark matter is considered in the context of a brane
world model in which the confinement of gauge fields on the brane is achieved
by invoking a confining potential. First, we show that the virial mass
discrepancy can be addressed if the conserved geometrical term appearing in
this model is considered as an energy momentum tensor of an unknown type of
matter, the so-called X-matter whose equation of state is also obtained.
Second, the galaxy rotation curves are explained by assuming an anisotropic
energy momentum tensor for the X-matter.Comment: 13 pages, 1 figure, to appear in IJMP
Generalized Chaplygin gas as geometrical dark energy
The generalized Chaplygin gas provides an interesting candidate for the
present accelerated expansion of the universe. We explore a geometrical
explanation for the generalized Chaplygin gas within the context of brane world
theories where matter fields are confined to the brane by means of the action
of a confining potential. We obtain the modified Friedmann equations,
deceleration parameter and age of the universe in this scenario and show that
they are consistent with the present observational data.Comment: 11 pages, 3 figures, to appear in PR
Brane-World Black Hole Solutions via a Confining Potential
Using a confining potential, we consider spherically symmetric vacuum (static
black hole) solutions in a brane-world scenario. Working with a constant
curvature bulk, two interesting cases/solutions are studied. A Schwarzschild-de
Sitter black hole solution similar to the standard solution in the presence of
a cosmological constant is obtained which confirms the idea that an extra term
in the field equations on the brane can play the role of a positive
cosmological constant and may be used to account for the accelerated expansion
of the universe. The other solution is one in which we can have a proper
potential to explain the galaxy rotation curves without assuming the existence
of dark matter and without working with new modified theories (modified
Newtonian dynamics).Comment: 12 pages, to appear in PR
Lagrangian description of world-line deviations
We introduce a Lagrangian which can be varied to give both the equation of
motion and world-line deviations of spinning particles simultaneously.Comment: to appear in IJT
Accelerating universe in brane gravity with a confining potential
We construct the Einstein field equations on a 4-dimensional brane embedded
in an -dimensional bulk where the matter fields are confined to the brane by
means of a confining potential. As a result, an extra term in the Friedmann
equation in a -dimensional bulk appears that may be interpreted as the
X-matter, providing a possible phenomenological explanation for the
acceleration of the universe. The study of the relevant observational data
suggests good agreement with the predictions of this model.Comment: 10 pages, 2 figures, to appear in Phys. Lett.
Worldline deviations of charged spinning particles
The geodesic deviation equation is generalized to worldline deviation
equations describing the relative accelerations of charged spinning particles
in the framework of Dixon-Souriau equations of motion
Virial mass in DGP brane cosmology
We study the virial mass discrepancy in the context of a DPG brane-world
scenario and show that such a framework can offer viable explanations to
account for the mass discrepancy problem. This is done by defining a
geometrical mass that we prove to be proportional to the virial
mass. Estimating using observational data, we show that it
behaves linearly with and has a value of the order of , pointing
to a possible resolution of the virial mass discrepancy. We also obtain the
radial velocity dispersion of galaxy clusters and show that it is compatible
with the radial velocity dispersion profile of such clusters. This velocity
dispersion profile can be used to differentiate various models predicting the
virial mass.Comment: 12 pages, 1 figure, to appear in CQ
Anisotropic brane gravity with a confining potential
We consider an anisotropic brane world with Bianchi type I and V geometries
where the mechanism of confining the matter on the brane is through the use of
a confining potential. The resulting equations on the anisotropic brane are
modified by an extra term that may be interpreted as the x-matter, providing a
possible phenomenological explanation for the accelerated expansion of the
universe. We obtain the general solution of the field equations in an exact
parametric form for both Bianchi type I and V space-times. In the special case
of a Bianchi type I the solutions of the field equations are obtained in an
exact analytic form. Finally, we study the behavior of the observationally
important parameters.Comment: 14 pages, 3 figures, to appear in PL
- …