Inflationary solutions in the simplest gravity model with conformal symmetry

TL;DR

This paper investigates a gravity model with conformal symmetry and finds that, in its simplest form, it does not produce inflationary solutions, indicating the need for more complex models to explain early Universe inflation.

Contribution

It demonstrates that the simplest conformal gravity model with Poincaré algebra terms cannot produce inflation, highlighting the necessity for extended models to achieve inflationary solutions.

Findings

No accelerated expansion in the simplest model

Five scalar fields arise from symmetry realization

More complex models are needed for inflation

Abstract

We discuss a model of gravity with conformal symmetry appearing in the simplest extension of General Relativity with the Poincar\'e algebra terms. The nonlinear realization of symmetry causes the existence of five scalar fields. Therefore it looks desirable to use them for driving the inflation at the earliest stages of the Universe evolution. It is shown that the evolution of the scale factor doesn't imply accelerated expansion so that there are no inflationary solutions in this model. To drive inflation a more complicated model induced by extension of the Poincare algebra is required.