# 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:

- 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}

}