Gravitational constraints of dS branes in an AdS Einstein-Brans-Dicke bulk

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Processo FAPESP: 09/01246-8

We derive the full projected Einstein-Brans-Dicke gravitational equations associated with an n-dimensional brane embedded in an (n + 1)-dimensional bulk. Using general conditions, as the positivity of the Brans-Dicke parameter and the effective Newton gravitational constant as well, we can constrain the brane cosmological constant in terms of the brane tension, the Brans-Dicke scalar field and the trace of the stress tensor on the brane, in order to achieve a dS brane. Applying these constraints to a specific five-dimensional model, a lower bound for the scalar field on the brane is elicited without solving the full equations. It is shown under which conditions the effective brane cosmological constant can be ignored in the brane projected gravitational field equations, suggesting a different fine tuning between the brane tension and the bulk cosmological constant.