New preinflation

Abstract

I propose a new model of preinflation, where the universe suffers a transition from an initial stable state [such that the universe is initially at the minimum of a ϕ-quartic potential: V(ϕ)∼ϕ4], to an unstable evolving state that drives the initial accelerated expansion. Using Relativistic Quantum Geometry (RQG), I demonstrate that back-reaction produced by the inflaton field fluctuations should be responsible for an additional term in the effective scalar potential. These fluctuations are very strong, and should cause the initial expansion of the universe when self-interactions of the inflaton fluctuations are included in its dynamics, even though it is initially in a stable state. The equation of state evolves from ω=−1∕3 to ω≲−1 and slow-roll conditions become naturally at the end of preinflation.