Cosmological Scaling Solutions and Multiple Exponential Potentials

TL;DR

This paper analyzes cosmological models with multiple scalar fields and exponential potentials, identifying stable scaling solutions and attractors that influence the universe's late-time behavior.

Contribution

It provides a phase-space analysis revealing new stable solutions and attractors for multiple scalar fields with exponential potentials in cosmology.

Findings

Power-law scaling solutions exist for flat positive and steep negative potentials.

The assisted inflationary solution is the unique late-time attractor for positive potentials.

Steep negative potentials have kinetically dominated attractors that are stable in expansion.

Abstract

We present a phase-space analysis of cosmology containing multiple scalar fields with positive and negative exponential potentials. We show that there exist power-law multi-kinetic-potential scaling solutions for sufficiently flat positive potentials or steep negative potentials. The former is the unique late-time attractor and the well-known assisted inflationary solution, but the later is never unstable in an expanding universe. Moreover, for steep negative potentials there exist a kinetic-dominated regime in which each solution is a late-time attractor. We briefly discuss the physical consequences of these results.