Flows into inflation: An effective field theory approach

TL;DR

This paper uses an effective field theory and dynamical-systems approach to analyze how generic single-clock systems can naturally evolve into inflationary states, identifying conditions for inflation persistence and universal potential forms.

Contribution

It introduces a novel method combining effective field theory with dynamical systems to study inflation flow, revealing universal potential forms and conditions for sustained inflation.

Findings

Significant probability for systems to flow into inflationary states.

Inflation can persist for at least 60 efolds in simple models.

Universal effective potential form similar to power-law inflation.

Abstract

We analyze the flow into inflation for generic "single-clock" systems, by combining an effective field theory approach with a dynamical-systems analysis. In this approach, we construct an expansion for the potential-like term in the effective action as a function of time, rather than specifying a particular functional dependence on a scalar field. We may then identify fixed points in the effective phase space for such systems, order-by-order, as various constraints are placed on the $M$th time derivative of the potential-like function. For relatively simple systems, we find significant probability for the background spacetime to flow into an inflationary state, and for inflation to persist for at least 60 efolds. Moreover, for systems that are compatible with single-scalar-field realizations, we find a single, universal functional form for the effective potential, $V (\phi)$, which is similar to the well-studied potential for power-law inflation. We discuss the compatibility of such dynamical systems with observational constraints.