Symmetries and assisted inflation in the DGP braneworld model

TL;DR

This paper explores symmetries in the DGP braneworld model's field equations, providing methods to generate new cosmological solutions and analyzing conditions for assisted inflation influenced by extra dimensions.

Contribution

It introduces a general transformation preserving the form of the field equations, enabling the creation of new cosmological models and examining inflation mechanisms in the DGP framework.

Findings

Identified symmetries that relate solutions with different equations of state.

Provided the first known exact DGP perfect fluid spacetime.

Showed that assisted inflation depends on the brane embedding and scalar fields.

Abstract

We present here the general transformation that leaves unchanged the form of the field equations for perfect fluid cosmologies in the DGP braneworld model. Specifically, a prescription for relating exact solutions with different equations of state is provided, and the symmetries found can be used as algorithms for generating new cosmological models from previously known ones. We also present, implicitly, the first known exact DGP perfect fluid spacetime. A particular case of the general transformation is used to illustrate the crucial role played both by the number of scalar fields and the extra dimensional effects in the occurrence of inflation. In particular, we see that assisted inflation does not proceed at all times for one of the two possible ways in which the brane can be embedded into the bulk.