4,243 research outputs found
Gauss-Bonnet Brane Cosmology with Radion Stabilization
We study cosmology in a five-dimensional brane-world with a stabilizing
effective potential for the radion and matter localized on the two branes. We
consider the corrections induced by the Gauss-Bonnet contribution to the total
action performing and expansion around the two possible static solutions up to
second order in the ratio between brane matter energy density and brane
tensions. The Friedmann and acceleration equations on the visible brane are
obtained and discussed.Comment: To be published in Phys.Rev.D, References Adde
Second order brane cosmology with radion stabilization
We study cosmology in the five-dimensional Randall-Sundrum brane-world with a
stabilizing effective potential for the radion and matter localized on the
branes. The analysis is performed by employing a perturbative expansion in the
ratio rho/V between the matter energy density on the branes and the brane
tensions around the static Randall-Sundrum solution (which has rho=0 and brane
tensions +-V). This approach ensures that the matter evolves adiabatically and
allows us to find approximate solutions to second order in \rho/V. Some
particular cases are then analyzed in details.Comment: 17 pages, RevTeX4, 4 figures, final version to appear in Phys. Rev.
Classical dynamics and stability of collapsing thick shells of matter
We study the collapse towards the gravitational radius of a macroscopic
spherical thick shell surrounding an inner massive core. This overall
electrically neutral macroshell is composed by many nested delta-like massive
microshells which can bear non-zero electric charge, and a possibly non-zero
cosmological constant is also included. The dynamics of the shells is described
by means of Israel's (Lanczos) junction conditions for singular hypersurfaces
and, adopting a Hartree (mean field) approach, an effective Hamiltonian for the
motion of each microshell is derived which allows to check the stability of the
matter composing the macroshell. We end by briefly commenting on the quantum
effects which may arise from the extension of our classical treatment to the
semiclassical level.Comment: 16 pages in IOP style, 8 figures, accepted for publication in Class.
Quantum Gra
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