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Title: Dynamics of scalar-tensor cosmology from a Randall-Sundrum two-brane model

Abstract

We consider a Randall-Sundrum two-brane cosmological model in the low energy gradient expansion approximation by Kanno and Soda. It is a scalar-tensor theory with a specific coupling function and a specific potential. Upon introducing the Friedmann-Lemaitre-Robertson-WalkerFLRW metric and perfect fluid matter on both branes in the Jordan frame, the effective dynamical equation for the A-brane (our Universe) scale factor decouples from the scalar field and B-brane matter leaving only a nonvanishing integration constant (the dark radiation term). We find exact solutions for the A-brane scale factor for four types of matter: cosmological constant, radiation, dust, and cosmological constant plus radiation. We perform a complementary analysis of the dynamics of the scalar field (radion) using phase space methods and examine convergence towards the limit of general relativity. In particular, we find that radion stabilizes at a certain finite value for suitable negative matter densities on the B-brane. Observational constraints from solar system experiments (PPN) and primordial nucleosynthesis (BBN) are also briefly discussed.

Authors:
; ;  [1]
  1. Institute of Physics, University of Tartu, Riia 142, Tartu 51014 (Estonia)
Publication Date:
OSTI Identifier:
20935207
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevD.75.023505; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; APPROXIMATIONS; CONVERGENCE; COSMOLOGICAL CONSTANT; COSMOLOGICAL MODELS; COSMOLOGY; EQUATIONS; EXACT SOLUTIONS; EXPANSION; GENERAL RELATIVITY THEORY; IDEAL FLOW; MATTER; NUCLEOSYNTHESIS; PHASE SPACE; POTENTIALS; SCALAR FIELDS; SCALARS; SOLAR SYSTEM; TENSORS; UNIVERSE

Citation Formats

Jaerv, Laur, Kuusk, Piret, and Saal, Margus. Dynamics of scalar-tensor cosmology from a Randall-Sundrum two-brane model. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.023505.
Jaerv, Laur, Kuusk, Piret, & Saal, Margus. Dynamics of scalar-tensor cosmology from a Randall-Sundrum two-brane model. United States. doi:10.1103/PHYSREVD.75.023505.
Jaerv, Laur, Kuusk, Piret, and Saal, Margus. Mon . "Dynamics of scalar-tensor cosmology from a Randall-Sundrum two-brane model". United States. doi:10.1103/PHYSREVD.75.023505.
@article{osti_20935207,
title = {Dynamics of scalar-tensor cosmology from a Randall-Sundrum two-brane model},
author = {Jaerv, Laur and Kuusk, Piret and Saal, Margus},
abstractNote = {We consider a Randall-Sundrum two-brane cosmological model in the low energy gradient expansion approximation by Kanno and Soda. It is a scalar-tensor theory with a specific coupling function and a specific potential. Upon introducing the Friedmann-Lemaitre-Robertson-WalkerFLRW metric and perfect fluid matter on both branes in the Jordan frame, the effective dynamical equation for the A-brane (our Universe) scale factor decouples from the scalar field and B-brane matter leaving only a nonvanishing integration constant (the dark radiation term). We find exact solutions for the A-brane scale factor for four types of matter: cosmological constant, radiation, dust, and cosmological constant plus radiation. We perform a complementary analysis of the dynamics of the scalar field (radion) using phase space methods and examine convergence towards the limit of general relativity. In particular, we find that radion stabilizes at a certain finite value for suitable negative matter densities on the B-brane. Observational constraints from solar system experiments (PPN) and primordial nucleosynthesis (BBN) are also briefly discussed.},
doi = {10.1103/PHYSREVD.75.023505},
journal = {Physical Review. D, Particles Fields},
number = 2,
volume = 75,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}
  • In the Randall-Sundrum two D-brane system, we derive the gravitational theory on the branes. It is turned out from the consistency that one D-brane has the negative tension brane under Randall-Sundrum tuning and both gauge fields on the brane are related by scale transformation through the bulk R(Ramond)R/NS(Neveu-Schwarz)-NS fields. As with the single D-brane case, the gauge field which is supposed to be localized on the brane does not couple to the gravity on the branes.
  • We analyze the Randall-Sundrum two D-brane model by linear perturbation and then consider the linearized gravity on the D brane. The qualitative contribution from the Kaluza-Klein modes of gauge fields to the coupling to the gravity on the brane will be addressed. As a consequence, the gauge fields localized on the brane are shown not to contribute to the gravity on the brane at large distances. Although the coupling between gauge fields and gravity appears in the next order, the ordinary coupling cannot be realized.
  • We discuss the cosmological implications and the holographic dual theory of the 7D Randall-Sundrum gravitational setup. Adding generic matter in the bulk on the 7D gravity side, we study the cosmological evolution inferred by the nonvanishing value of the brane-bulk energy exchange parameter. This analysis is achieved in detail for specific assumptions on the internal space evolution, including analytical considerations and numerical results. The dual theory is then constructed, making use of the holographic renormalization procedure. The resulting renormalized 6D conformal field theory is anomalous and coupled to 6D gravity plus higher order corrections. The critical point analysis on themore » brane is performed. Finally, we sketch a comparison between the two dual descriptions. We moreover generalize the Ads/CFT dual theory to the nonconformal and interacting case, relating the energy exchange parameter of the bulk gravity description to the new interactions between hidden and visible sectors.« less
  • In our previous work of [K. Farakos and P. Pasipoularides, Phys. Lett. B 621, 224 (2005).] we studied the stability of the RS2 model with a nonminimally coupled bulk scalar field {phi}, and we found that in appropriate regions of {xi} the standard RS2 vacuum becomes unstable. The question that arises is whether there exists other new static stable solutions where the system can relax. In this work, by solving numerically the Einstein equations with the appropriate boundary conditions on the brane, we find that depending on the value of the nonminimal coupling {xi}, this model possesses three classes ofmore » new static solutions with different characteristics. We also examine what happens when the fine-tuning of the RS2 model is violated, and we obtain that these three classes of solutions are preserved in appropriate regions of the parameter space of the problem. The stability properties and possible physical implications of these new solutions are discussed in the main part of this paper. Especially in the case where {xi}={xi}{sub c} ({xi}{sub c} is the five-dimensional conformal coupling) and the fine-tuning is violated, we obtain a physically interesting static stable solution.« less
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