Gauge invariant backreaction in general single field models of inflation

Understand

In a general single field inflationary model we consider the effects of long wavelength scalar fluctuations on the effective expansion rate and equation of state seen by a class of free falling observers, using a physical gauge invariant formulation.

• In a previous work we showed that for a free massive inflaton no backreaction is observed within some constraints.
• In this paper we extend the validity of our previous results to the case of an arbitrary self-interacting inflation potential, working to second order in cosmological perturbation theory and to all order in slow-roll approximation.
• For these general inflationary models, we also show the equivalence of the free falling observers to the ones comoving with the inflaton field.