Some Cosmological Consequences of Weyl Invariance

TL;DR

This paper explores Weyl invariant cosmological models with conformally coupled scalar fields, demonstrating that accelerated expansion naturally emerges as a solution within this framework.

Contribution

It introduces a class of Weyl invariant cosmological models with multiple scalar fields and shows that accelerated expansion can be a natural solution.

Findings

Accelerated expansion arises naturally in Weyl invariant models.

Conformal invariance ensures gravitational equations hold with scalar field solutions.

Any scale factor can be a solution given a suitable dilaton profile.

Abstract

We examine some Weyl invariant cosmological models in the framework of generalized dilaton gravity, in which the action is made of a set of $N$ conformally coupled scalar fields. It will be shown that when the FRW ansatz for the spacetime metric is assumed, the Ward identity for conformal invariance guarantees that the gravitational equations hold whenever the scalar fields EM do so. It follows that any scale factor can solve the theory provided a non-trivial profile for a dilaton field. In particular, accelerated expansion is a natural solution to the full set of equations.