4,229 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.
On boundary terms and conformal transformations in curved space-times
We intend to clarify the interplay between boundary terms and conformal
transformations in scalar-tensor theories of gravity. We first consider the
action for pure gravity in five dimensions and show that, on compactifing a la
Kaluza-Klein to four dimensions, one obtains the correct boundary terms in the
Jordan (or String) Frame form of the Brans-Dicke action. Further, we analyze
how the boundary terms change under the conformal transformations which lead to
the Pauli (or Einstein) frame and to the non-minimally coupled massless scalar
field. In particular, we study the behaviour of the total energy in
asymptotically flat space-times as it results from surface terms in the
Hamiltonian formalism.Comment: LaTeX 2e, 12 pages, no figure
- …