Article
Exactly solvable model for cosmological perturbations in dilatonic brane worlds
Physical review D: Particles and fields 07/2003; DOI: 10.1103/PhysRevD.68.103512
Source: arXiv

Article: Models for the branebulk interaction: Toward understanding braneworld cosmological perturbations
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ABSTRACT: Using some simple toy models, we explore the nature of the branebulk interaction for cosmological models with a large extra dimension. We are in particular interested in understanding the role of the bulk gravitons, which from the point of view of an observer on the brane will appear to generate dissipation and nonlocality, effects that cannot be incorporated into an effective (3+1)dimensional Lagrangian field theoretic description. We explicitly work out the dynamics of several discrete systems consisting of a finite number of degrees of freedom on the boundary coupled to a (1+1)dimensional field theory subject to a variety of wave equations. Systems both with and without time translation invariance are considered and moving boundaries are discussed as well. The models considered contain all the qualitative features of quantized linearized cosmological perturbations for a RandallSundrum universe having an arbitrary expansion history, with the sole exception of gravitational gauge invariance, which will be treated in a later paper.Physical Review D 01/2004; 70(4). · 4.69 Impact Factor 
Article: Scalar cosmological perturbation in an inflationary brane world driven by the bulk inflaton
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ABSTRACT: We investigate scalar perturbations from inflation in a bulk inflaton braneworld model. Using the generalized longitudinal gauge, we derive and solve the full set of scalar perturbation equations. Our exact results support the recent argument that for the de Sitter brane the square of the radion mass is not positive, showing that unlike the flat brane case, the de Sitter brane is not stable. Comment: 17pages, Latex formatInternational Journal of Modern Physics A 12/2003; · 1.13 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The Dvali, Gabadadze and Porrati (DGP) model has a selfaccelerating solution, the positive branch, where the brane is asymptotically de Sitter. A de Sitter space–time can be seen as a boundary between quintessencelike behaviour and phantomlike behaviour. We show that in a 5D dilatonic bulk, where the dilaton has an exponential potential, with an induced gravity term on the brane, whose matter content corresponds only to vacuum energy, the positive branch solution undergoes a phantomlike stage where it faces a curvature singularity in its infinite future. The singularity can be interpreted as the “big rip” singularity pushed towards an infinite future cosmic time. The phantomlike behaviour on the brane occurs without violating the null energy condition. There is another solution, the negative branch, where the brane can undergo an earlyepoch (transient) inflationary phase induced by the dilaton field.Nuclear Physics B 07/2008; · 4.33 Impact Factor
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