$R^2$ inflation to probe non-perturbative quantum gravity

Understand

It is natural to expect a consistent inflationary model of the very early Universe to be an effective theory of quantum gravity, at least at energies much less than the Planck one.

• For the moment, $R+R^2$, or shortly $R^2$, inflation is the most successful in accounting for the latest CMB data from the PLANCK satellite and other experiments.
• Moreover, recently it was shown to be ultra-violet (UV) complete via an embedding into an analytic infinite derivative (AID) non-local gravity.
• In this paper, we derive a most general theory of gravity that contributes to perturbed linear equations of motion around maximally symmetric space-times.